Method for producing RNA

ABSTRACT

The present invention relates to a method for producing RNA. In particular, the present invention relates to a method for producing RNA, which is scalable and provides RNA at a high purity. The present invention provides a method for producing RNA under GMP and/or cGMP-compliant conditions. The invention further provides specific processes for use as a quality control in the manufacturing of a template DNA and/or in a method for producing RNA, in particular by in vitro transcription.

This application is a continuation of International Application No.PCT/EP2015/000959, filed May 8, 2015, the entirety of which isincorporated herein by reference.

The present invention relates to a method for producing RNA. Inparticular, the present invention relates to a method for producing RNA,which is scalable and provides RNA at a high purity. The presentinvention provides a method for producing RNA under GMP and/orcGMP-compliant conditions. The invention further provides specificprocesses for use as a quality control in the manufacturing of atemplate DNA and/or in a method for producing RNA, in particular by invitro transcription.

Molecular medicine aims at curing or preventing numerous diseases byemploying various therapeutic approaches, such as gene therapy andgenetic vaccination. Such approaches are frequently based on theintroduction of nucleic acids, such as DNA or RNA, into a subject's cellor tissue, followed by the translation of the information coded by thenucleic acids into the desired polypeptides or proteins.

Genetic vaccinations, pioneered by injecting naked plasmid DNA, weredemonstrated in the early 1990s on mice. However, during clinical trials(phase I/II clinical studies) it became clear that this technology wasunable to fulfil the expectations in humans that have been aroused bythe studies in mice.

1990 Wolff et al. showed that the injection of naked genetic informationin the form of plasmid DNA or mRNA can lead to protein expression inmice (Science. 1990 Mar. 23; 247(4949 Pt 1):1465-8). These results werefollowed by investigations which showed that naked plasmid DNA can beused for vaccination. The use of mRNA for vaccination, however, was paidlittle attention until the late 1990s, when it was demonstrated that thetransfer of mRNA into dendritic cells triggers immune responses. Thedirect injection of mRNA for vaccination remained a marginal theme. Oneof the main reasons for this was the instability of mRNA due to itsrapid degradation by ribonucleases and the associated limitedeffectiveness of the mRNA as a genetic tool in vivo. In the meantime,however, numerous methods for stabilizing mRNA have been described inthe prior art, for example in EP-A-1083232, WO 99/14346, U.S. Pat. No.5,580,859 and U.S. Pat. No. 6,214,804.

RNA as the nucleic acid for a genetic vehicle has numerous advantagesover DNA, including:

i) The RNA introduced into the cell does not integrate into the genome(whereas DNA does integrate into the genome to a certain degree and canalso be inserted into an intact gene of the genome of the host cell,causing a mutation of this gene, which can lead to a partial or totalloss of the genetic information or to misinformation).ii) No viral sequences, such as promoters etc., are required for theeffective transcription of RNA (whereas a strong promoter (e.g. theviral CMV promoter) is required for the expression of DNA introducedinto the cell). The integration of such promoters into the genome of thehost cell can lead to undesirable changes in the regulation of geneexpression.iii) The degradation of RNA that has been introduced takes place in alimited period of time, so that it is possible to achieve transient geneexpression, which can be discontinued after the required treatmentperiod (whereas this is not possible in the case of DNA that has beenintegrated into the genome).iv) RNA does not lead to the induction of pathogenic anti-RNA antibodiesin the patient (whereas the induction of anti-DNA antibodies is known tocause an undesirable immune response).v) RNA is widely applicable; any desired RNA for any desired protein ofinterest can be prepared in short period of time for therapeuticpurposes, even on an individual patient basis (personalized medicine).

In summary, it remains to be emphasized that mRNA represents a transientcopy of the coded genetic information in all organisms, serves as amodel for the synthesis of proteins and, unlike DNA, represents all thenecessary prerequisites for the preparation of a suitable vector for thetransfer of exogenous genetic information in vivo.

These beneficial characteristics of mRNA were discovered in the recentyears and clinical development of mRNA-based therapeutics is in progress(reviewed in Sahin et al. 2014. Nat Rev Drug Discov. 2014 October;13(10):759-80. doi: 10.1038/nrd4278. Epub 2014 Sep. 19. And Kallen andThess 2014. Ther Adv Vaccines. 2014 January; 2(1):10-31. doi:10.1177/2051013613508729. Review).

By then, the synthesis of in vitro transcribed mRNA at a laboratoryscale (up to 1 mg), produced under non-GMP (good manufacturing practice)conditions was the technical standard in the art.

For this reason, several methods for improving the production of invitro transcribed RNA were developed. Pascolo 2006 (Methods Mol Med.2006; 127:23-40.) and Probst et al. (2012 Messenger RNA Vaccines GeneVaccines, Springer Vienna, ISBN 978-3-7091-0438-5) describe theprinciples of the production of pharmaceutical grade mRNA, which isperformed in vitro in a reaction termed run-off transcription, where thetemplate plasmid DNA (pDNA) contains an RNA polymerase promoter and allstructural mRNA elements (except the 5′ Cap and, in some protocols, the3′ poly(A) tail). Purified plasmid DNA is linearized bysequence-specific cleavage with a restriction enzyme to ensure definedtermination of transcription and is then used as a DNA template for RNAin vitro transcription. Besides linearized template DNA, the in vitrotranscription reaction mixture contains reaction buffer, recombinant RNApolymerase, nucleotides and, in some protocols, Cap analogue.Alternative protocols include a separate enzymatic capping reactionafter transcription. Transcription stops as the RNA polymerase reachesthe end of the DNA template releasing both the template DNA and thenewly synthesized mRNA. Polyadenylation of the mRNA molecule is eitherencoded on the pDNA by a poly(T) sequence of about 50 nucleotides andadded during the in vitro transcription reaction, or by synthetizing thepoly-A tail enzymatically in a post-transcriptional step. Finally,different protocols are employed to purify the mRNA product, all ofwhich include a step of nuclease digestion for subsequent removal oftemplate DNA.

Furthermore it was shown that a current good manufacturing practice(cGMP)-compliant chromatographic method increases the activity ofintroduced mRNA molecules up to about five times (regarding proteinexpression in vivo) (Probst et al, Gene Ther. 2007 August;14(15):1175-80. Epub 2007 May 3 and WO2008077592).

Some prior art documents concern specific aspects of the production ofin vitro transcribed RNA:

WO2014/152027 describes methods for production of RNA transcripts usinga non-amplified, linearized DNA template in an RNA in vitrotranscription reaction. These methods include the linearization ofplasmid DNA as template for the in vitro transcription reaction, invitro transcription and several purification steps between the differentsteps of the method.

WO2014/144039 describes several methods for characterizing samplescomprising RNA transcripts including oligonucleotide mapping, reversetranscriptase sequencing, charge distribution analysis, or detection ofRNA impurities.

WO2008/077592 discloses a method for purifying large RNA on apreparative scale with ion-pairing reversed phase HPLC using a porousreversed stationary phase. It is reported that a particular advantage ofusing the specified porous stationary phase is that excessively highpressures can be avoided, facilitating a preparative purification ofRNA. However, the method involves the use of harsh organic solvents(e.g. acetonitrile) and high temperatures (78° C.) for the separationcolumn, and a low temperature (12° C.) for the sampler. The nature ofthe contaminant(s) that can be successfully separated from a desired RNAusing the method is not exemplified, including any requirements forpreceding steps such as DNase treatment. Additionally, chromatographicseparation of RNA based on ion-pairing reversed phase HPLC or ionexchange resin are based on the molecule's total charge and may beeffective for purification of RNA molecules of up to about 4,000-5,000bases.

As illustrated above, RNA is emerging as an innovative candidate for avariety of pharmaceutical applications, but efficient large-scaleproduction, in particular under current good manufacturing practice(cGMP) or GMP compliance, continues to be a challenge.

However, for example, for conducting preclinical and clinical trials andcommercialization as human therapeutic, and in order to produce a largeamount of RNA, e.g. RNA vaccine in a pandemic scenario, an up-scaledcGMP or GMP-compliant production process needs to be developed andestablished. Such a process should be capable of producing at least 1 gmRNA, preferably at least 5 g, or more preferably at least 10 g mRNA perbatch.

So far, no cGMP or GMP-compliant production process for manufacturing invitro transcribed RNA at a large scale, including (c)GMP-compliantquality controls, is described in the art. A (c)GMP compliant productionprocess has to ensure the consistent production of a homogeneousultra-pure (no contaminations from individual production steps, such astemplate DNA or bacterial DNA), sterile, non-pyrogenic (endotoxin free)and stable mRNA medicament in a highly reproducible manner (that is: nobatch-to-batch variability). Effective quality controls are thusrequired for intermediates in the production process (e.g. plasmid DNA)as well as for the end products (mRNA/formulated mRNA). A(c)GMP-compliant production process is a prerequisite to furtherestablish mRNA as a powerful therapeutic tool in modern molecularmedicine. Therefore, there is an urgent need to establish a(c)GMP-compliant mRNA production process.

Moreover, there is an unmet need of an effective method for determiningthe homogeneity and physical-chemical integrity of RNA transcripts forclinical. Methods for determining the homogeneity and physical-chemicalintegrity of RNA manufactured for use as a human therapeutic are neededin order to demonstrate consistency of production batches and formaintaining safety and efficacy of the therapeutic product duringlong-term storage. Furthermore, in order to facilitate industrialapplications, the RNA manufacturing process must enable consistent,cost- and time-efficient operation (e.g. quick, easy, reproducible, highyield) on a large scale, preferably in compliance with (c)GMP.

It is one object of the present invention to develop a scalable currentgood manufacturing practice (c)GMP-compliant production processincluding appropriate quality controls to produce RNA of a high qualityin large quantities. It is further an object of the present invention toprovide a scalable method for producing RNA, which preferably allowsproduction of RNA for clinical use, on a large scale. In particular, itis an object of the present invention to provide a method for producingRNA, in particular for producing RNA under (c)GMP compliant conditions,wherein the method is suitable for industrial application. Inparticular, RNA should be provided without contaminations, such astemplate DNA or bacterial DNA. A further object underlying the presentinvention is the provision of a method for determining the quality,especially the homogeneity and/or physical-chemical integrity, of invitro produced RNA. In particular, it is an object of the presentinvention to provide a method for controlling the quality of RNAproduced in vitro, wherein the method is preferably applicable in a(c)GMP compliant environment.

The problem underlying the present invention is solved by the claimedsubject-matter.

The present invention provides a method for producing RNA, particularlyan mRNA molecule, suitable for manufacturing clinical-grade RNA of highpurity, reproducibly and in compliance with (c)GMP. In particular, thepresent invention provides a method for producing RNA as defined by theclaims and the description herein.

In a particular aspect, the present invention concerns a method forproducing RNA comprising the following steps:

a) providing a template DNA comprising a nucleic acid sequence encodingan RNA sequence;

b) in vitro transcription of the template DNA in order to obtain acomposition comprising the RNA;

wherein the method comprises

at least one step for controlling the quality of the template DNAprovided in step a),

wherein the at least one step for controlling the quality of thetemplate DNA comprises at least one selected from the group consistingof determining the concentration of the template DNA in a sample,determining the integrity of the template DNA, determining the identityof the template DNA, and determining the purity of the template DNA;and/orat least one step for controlling the quality of the RNA obtained instep b),wherein the at least one step for controlling the quality of the RNAobtained in step b) comprises at least one step selected from the groupconsisting of determining the concentration of the RNA in a sample,determining the integrity of the RNA, determining the identity of theRNA, determining the purity of the RNA, determining the pH of a samplecomprising the RNA, determining the osmolality of a sample comprisingthe RNA, determining the presence and/or the amount of the template DNAin a sample comprising the RNA, and determining the presence and/or theamount of an organic solvent in a sample comprising the RNA.

It has surprisingly been found by the inventors that the inventivemethod, in particular the specific combination of steps as definedherein, is suitable for large-scale production of highly pure RNA, inparticular in a GMP or cGMP-compliant manner.

Disclosed herein are methods for production of RNA transcripts,particularly mRNA, useful for manufacturing RNA of excellent purity at alarge scale, reproducibly and in compliance with (c)GMP. The majorproduction steps preferably include the provision of a template DNA forin vitro transcription, e.g. by cloning the gene or sequence of interestinto an appropriate plasmid DNA vector (see also FIG. 1). In anotherstep, an in vitro transcription reaction is performed using the templateDNA, preferably as defined herein, as a template. For example, a plasmidDNA template may be linearized using restriction endonucleases to ensuredefined termination of the subsequent run-off in vitro transcription.The template DNA serves as a template for enzymatic RNA in vitrotranscription. In certain embodiments, the RNA product is lyophilizedand formulated after removal of the template DNA and RNA purification.

An aspect of the present invention relates to at least one purificationstep, preferably a combination of purification steps, which allows toefficiently remove a starting material or a by-product of any upstreammanufacturing processes, including organic solvents, enzymes, bacterialcontaminations, DNA contaminations and the like.

Another aspect of the present invention is that along with a definedproduction step, and/or a defined purification step, quality controlsare performed in compliance with a (c)GMP production. Moreover, severalquality end-control measurements are preferably performed with the finalRNA product to ensure product safety, ensuring a drug-safety-profile ofa clinical-grade RNA medicament. These measurements include thedetection of potentially hazardous contaminations during the productionprocess (e.g., endotoxin, bacterial DNA, DNA contaminations, bacterialcontaminations, contaminations with organic solvents) and the like.Moreover, quality and integrity of intermediates of the method aremonitored. In a specific aspect, the invention provides a method forcontrolling the quality of the RNA product or any intermediate in aprocess for producing RNA, preferably a process for producing RNA by invitro transcription. In a particular aspect, the invention provides amethod for controlling the quality of a templated DNA used in such aprocess and/or the quality of an RNA (final product or intermediate)obtained in a process for producing RNA.

The inventive manufacturing process, in particular if includingpurification steps and quality controls, ensures the production of ahomogeneous ultra-pure (no contaminations with product intermediates,enzymes, solvents), sterile, non-pyrogenic (endotoxin free) and stableRNA, e.g. an mRNA medicament, being manufactured in a highlyreproducible manner.

The present invention thus represents a milestone to further establishRNA particularly mRNA as an inventive therapeutic tool in modernmolecular medicine.

For the sake of clarity and readability, the following definitions areprovided. Any technical feature mentioned for these definitions may beread on each and every embodiment of the invention. Additionaldefinitions and explanations may be specifically provided in the contextof these embodiments.

Enzyme: Enzymes are catalytically active biomolecules that performbiochemical reactions such as DNA dependent RNA transcription (e.g., RNApolymerases), or double stranded DNA digestion (e.g., restrictionendonucleases). Enzymes are typically composed of amino acids and/or RNA(ribozymes, snRNA).Restriction endonucleases: Restriction endonucleases or restrictionenzymes are a class of enzymes that occur naturally in bacteria and insome viruses. Restriction endonucleases can be used in the laboratory tocleave DNA molecules into smaller fragments for molecular cloning andgene characterization. Restriction enzymes bind specifically to andcleave double-stranded DNA at specific sites within or adjacent to aparticular sequence known as the recognition site. Most of therestriction enzymes recognize a specific sequence of nucleotides thatare four, five or six nucleotides in length and display twofoldsymmetry. Some cleave both strands exactly at the axis of symmetry,generating fragments of DNA that carry blunt ends; others cleave eachstrand at similar locations on opposite sides of the axis of symmetry,creating fragments of DNA that carry single-stranded termini (cohesiveends). The restriction endonucleases are categorized into four groups(Types I, II, III, and IV) based on their composition and enzymecofactor requirements, the nature of their target sequence, and theposition of their DNA cleavage site relative to the target sequence. Alltypes of enzymes recognize specific short DNA sequences and carry outthe cleavage of DNA, yielding specific fragments with terminal5′-phosphates. Restriction endonucleases recognize and bind particularsequences of nucleotides (the ‘recognition site’) on DNA molecules. Oncebound, they cleave the molecule within (e.g., BamHI), to one side of(e.g., SapI), or to both sides (e.g., TspRI) of the recognitionsequence. Particularly preferred is the use of the following restrictionenzymes: BciVI (BfuI), BcuI (SpeI), EcoRI, AatII, AgeI (BshTI), ApaI,BamHI, BglII, BlpI (Bpu1102I), BsrGI (Bsp1407), ClaI (Bsu15I), EcoRI,EcoRV (Eco32I), HindIII, KpnI, MluI, NcoI, NdeI, NheI, NotI, NsiI,Mph1103I), PstI, PvuI, PvuII, SacI, SalI, ScaI, SpeI, XbaI, XhoI, SacII(Cfr42I), XbaI. Restriction enzymes recognize short DNA sequences andcleave double-stranded DNA at specific sites within or adjacent to thesesequences. Approximately 3,000 restriction enzymes, recognizing over 230different DNA sequences, have been discovered. They have been foundmostly in bacteria, but have also been isolated from viruses, archaeaand eukaryotes. A list of known restriction enzymes can be found at therebase database:http://rebase.neb.com/rebase/rebase.htmlRestriction site: A restriction site, also termed restriction enzymerecognition site, is a nucleotide sequence recognized by a restrictionenzyme. A restriction site is typically a short, preferably palindromicnucleotide sequence, e.g. a sequence comprising 4 to 8 nucleotides. Arestriction site is preferably specifically recognized by a restrictionenzyme. The restriction enzyme typically cleaves a nucleotide sequencecomprising a restriction site at this site. In a double-strandednucleotide sequence, such as a double-stranded DNA sequence, therestriction enzyme typically cuts both strands of the nucleotidesequence. Most restriction endonucleases recognize palindromic orpartially palindromic sites. A palindrome is defined as dyad symmetryaround an axis. For example, EcoRI digestion produces “sticky” ends,whereas SmaI restriction enzyme cleavage produces “blunt” ends.Recognition sequences in DNA differ for each restriction enzyme,producing differences in the length, sequence and strand orientation (5′end or the 3′ end) of a sticky-end “overhang” of an enzyme restriction.Different restriction enzymes that recognize the same sequence are knownas neoschizomers. These often cleave in different locales of thesequence. Different enzymes that recognize and cleave in the samelocation are known as isoschizomers.Protein: A protein typically comprises one or more peptides orpolypeptides. A protein is typically folded into 3-dimensional form,which may be required for the protein to exert its biological function.The sequence of a protein or peptide is typically understood to be theorder, i.e. the succession of its amino acids.Recombinant protein: The term ‘recombinant protein’ refers to proteinsthat have been produced in a heterologous system, that is, in anorganism that naturally does not produce such a protein, or a variant ofsuch a protein. Typically, the heterologous systems used in the art toproduce recombinant proteins are bacteria (e.g., Escherichia coli),yeast (e.g., Saccharomyces cerevisiae) or certain mammalian cell culturelines.Plasmid DNA (vectors): The term ‘plasmid DNA’ or ‘plasmid DNA vector’refer to a circular nucleic acid molecule, preferably to an artificialnucleic acid molecule. A plasmid DNA in the context of the presentinvention is suitable for incorporating or harboring a desired nucleicacid sequence, such as a nucleic acid sequence comprising a sequenceencoding an RNA and/or an open reading frame encoding at least onepeptide or polypeptide. Such plasmid DNA constructs/vectors may bestorage vectors, expression vectors, cloning vectors, transfer vectorsetc. A storage vector is a vector, which allows the convenient storageof a nucleic acid molecule, for example, of an RNA molecule. Thus, theplasmid DNA may comprise a sequence corresponding (coding for), e.g., toa desired RNA sequence or a part thereof, such as a sequencecorresponding to the open reading frame and the 5′- and/or 3′UTR of anmRNA. An expression vector may be used for production of expressionproducts such as RNA, e.g. mRNA in a process called RNA in vitrotranscription. For example, an expression vector may comprise sequencesneeded for RNA in vitro transcription of a sequence stretch of thevector, such as a promoter sequence, e.g. an RNA promoter sequence,preferably T3, T7 or SP6 RNA promotor sequences. A cloning vector istypically a vector that contains a cloning site, which may be used toincorporate nucleic acid sequences (insert) into the vector. A cloningvector may be, e.g., a plasmid vector or a bacteriophage vector. Atransfer vector may be a vector, which is suitable for transferringnucleic acid molecules into cells or organisms, for example, viralvectors. Preferably, a plasmid DNA vector in the sense of the presentinvention comprises a multiple cloning site, an RNA promoter sequence,optionally a selection marker, such as an antibiotic resistance factor,and a sequence suitable for multiplication of the vector, such as anorigin of replication. Particularly preferred in the context of thepresent invention are plasmid DNA vectors, or expression vectors,comprising promoters for DNA-dependent RNA polymerases such as T3, T7and Sp6. As plasmid backbone, particularly preferred are pUC19 andpBR322.Template DNA: As used herein, the term ‘template DNA’ (or DNA template′)typically relates to a DNA molecule comprising a nucleic acid sequenceencoding the RNA sequence to be in vitro transcribed. The template DNAis used as template for in vitro transcription in order to produce theRNA encoded by the template DNA. Therefore, the template DNA comprisesall elements necessary for in vitro transcription, particularly apromoter element for binding of a DNA dependent RNA polymerase as e.g.T3, T7 and SP6 RNA polymerases 5′ of the DNA sequence encoding thetarget RNA sequence. Furthermore the template DNA may comprise primerbinding sites 5′ and/or 3′ of the DNA sequence encoding the target RNAsequence to determine the identity of the DNA sequence encoding thetarget RNA sequence e.g. by PCR or DNA sequencing. As used herein, theterm ‘template DNA’ may also refer to a DNA vector, such as a plasmidDNA, which comprises a nucleic acid sequence encoding the RNA sequence.Further, the ‘template DNA’ in the context of the present invention maybe a linear or a circular DNA molecule.Target Sequence: A ‘target sequence’ as used herein is typicallyunderstood as the sequence of the RNA, which is encoded by the nucleicacid sequence comprised in the template DNA. The target sequence is thusthe sequence to be synthesized by in vitro transcription, e.g. aprotein-coding sequence or another RNA as defined herein like isRNA,antisense RNA etc.Linear template DNA plasmid: The linear template DNA plasmid is obtainedby contacting the plasmid DNA with a restriction enzyme under suitableconditions so that the restriction enzyme cuts the plasmid DNA at itsrecognition site(s) and disrupts the plasmid structure. Hence, thelinear template DNA comprises a free 5′ end and a free 3′ end, which arenot linked to each other. If the plasmid DNA contains only onerecognition site for the restriction enzyme, the linear template DNA hasthe same number of nucleotides as the plasmid DNA. If the plasmid DNAcontains more than one recognition site for the restriction enzyme, thelinear template DNA has a smaller number of nucleotides than the plasmidDNA. The linear template DNA is then the fragment of the plasmid DNA,which contains the elements necessary for RNA in vitro transcription,that is a promoter element for RNA transcription and the template DNAelement. The DNA sequence encoding the target RNA sequence of the lineartemplate DNA determines the sequence of the transcribed RNA by the rulesof base-pairing.5′-cap: A 5′-cap is an entity, typically a modified nucleotide entity,which generally “caps” the 5′-end of a mature mRNA. A 5′-cap maytypically be formed by a modified nucleotide, particularly by aderivative of a guanine nucleotide. Preferably, the 5′-cap is linked tothe 5′-terminus via a 5′-5′-triphosphate linkage. A 5′-cap may bemethylated, e.g. m7GpppN, wherein N is the terminal 5′ nucleotide of thenucleic acid carrying the 5′-cap, typically the 5′-end of an RNA.Further examples of 5′cap structures include glyceryl, inverted deoxyabasic residue (moiety), 4′,5′ methylene nucleotide,1-(beta-D-erythrofuranosyl) nucleotide, 4′-thio nucleotide, carbocyclicnucleotide, 1,5-anhydrohexitol nucleotide, L-nucleotides,alpha-nucleotide, modified base nucleotide, threo-pentofuranosylnucleotide, acyclic 3′,4′-seco nucleotide, acyclic 3,4-dihydroxybutylnucleotide, acyclic 3,5 dihydroxypentyl nucleotide, 3′-3′-invertednucleotide moiety, 3′-3′-inverted abasic moiety, 3′-2′-invertednucleotide moiety, 3′-2′-inverted abasic moiety, 1,4-butanediolphosphate, 3′-phosphoramidate, hexylphosphate, aminohexyl phosphate,3′-phosphate, 3′phosphorothioate, phosphorodithioate, or bridging ornon-bridging methylphosphonate moiety. Further modified 5′-CAPstructures which may be used in the context of the present invention areCAP1 (methylation of the ribose of the adjacent nucleotide of m7GpppN),CAP2 (methylation of the ribose of the 2nd nucleotide downstream of them7GpppN), CAP3 (methylation of the ribose of the 3rd nucleotidedownstream of the m7GpppN), CAP4 (methylation of the ribose of the 4thnucleotide downstream of the m7GpppN), ARCA (anti-reverse CAP analogue,modified ARCA (e.g. phosphothioate modified ARCA), inosine,N1-methyl-guanosine, 2′-fluoro-guanosine, 7-deaza-guanosine,8-oxo-guanosine, 2-amino-guanosine, LNA-guanosine, and2-azido-guanosine.Poly(A) sequence: A poly(A) sequence, also called poly(A) tail or3′-poly(A) tail, is typically understood to be a sequence of adeninenucleotides, e.g., of up to about 400 adenine nucleotides, e.g. fromabout 20 to about 400, preferably from about 50 to about 400, morepreferably from about 50 to about 300, even more preferably from about50 to about 250, most preferably from about 60 to about 250 adeninenucleotides. A poly(A) sequence is typically located at the 3′end of anmRNA. In the context of the present invention, a poly(A) sequence may belocated within an mRNA or any other nucleic acid molecule, such as,e.g., in a vector, for example, in a vector serving as template for thegeneration of an RNA, preferably an mRNA, e.g., by transcription of thevector.RNA, mRNA: RNA is the usual abbreviation for ribonucleic acid. It is anucleic acid molecule, i.e. a polymer consisting of nucleotide monomers.These nucleotides are usually adenosine-monophosphate,uridine-monophosphate, guanosine-monophosphate andcytidine-monophosphate monomers, which are connected to each other alonga so-called backbone. The backbone is formed by phosphodiester bondsbetween the sugar, i.e. ribose, of a first and a phosphate moiety of asecond, adjacent monomer. The specific order of the monomers, i.e. theorder of the bases linked to the sugar/phosphate-backbone, is called theRNA-sequence. Usually RNA may be obtainable by transcription of aDNA-sequence, e.g., inside a cell. In eukaryotic cells, transcription istypically performed inside the nucleus or the mitochondria. In vivo,transcription of DNA usually results in the so-called premature RNA,which has to be processed into so-called messenger-RNA, usuallyabbreviated as mRNA. Processing of the premature RNA, e.g. in eukaryoticorganisms, comprises a variety of differentposttranscriptional-modifications such as splicing, 5′-capping,polyadenylation, export from the nucleus or the mitochondria and thelike. The sum of these processes is also called maturation of RNA. Themature messenger RNA usually provides the nucleotide sequence that maybe translated into an amino acid sequence of a particular peptide orprotein. Typically, a mature mRNA comprises a 5′-cap, optionally a5′UTR, an open reading frame, optionally a 3′UTR and a poly(A) sequence.Aside from messenger RNA, several non-coding types of RNA exist whichmay be involved in regulation of transcription and/or translation, andimmunostimulation. The term “RNA” further encompass other coding RNAmolecules, such as viral RNA, retroviral RNA and replicon RNA, smallinterfering RNA (siRNA), antisense RNA, CRISPR RNA, ribozymes, aptamers,riboswitches, immunostimulating RNA, transfer RNA (tRNA), ribosomal RNA(rRNA), small nuclear RNA (snRNA), small nucleolar RNA (snoRNA),microRNA (miRNA), and Piwi-interacting RNA (piRNA).5′-untranslated region (5′-UTR): As used herein, the term ‘5′-UTR’typically refers to a particular section of messenger RNA (mRNA). It islocated 5′ of the open reading frame of the mRNA. Typically, the 5′-UTRstarts with the transcriptional start site and ends one nucleotidebefore the start codon of the open reading frame. The 5′-UTR maycomprise elements for controlling gene expression, also calledregulatory elements. Such regulatory elements may be, for example,ribosomal binding sites or a 5′-Terminal Oligopyrimidine Tract. The5′-UTR may be post-transcriptionally modified, for example by additionof a 5′-CAP. In the context of the present invention, a 5′-UTRcorresponds to the sequence of a mature mRNA, which is located betweenthe 5′-CAP and the start codon. Preferably, the 5′-UTR corresponds tothe sequence, which extends from a nucleotide located 3′ to the 5′-CAP,preferably from the nucleotide located immediately 3′ to the 5′-CAP, toa nucleotide located 5′ to the start codon of the protein coding region,preferably to the nucleotide located immediately 5′ to the start codonof the protein coding region. The nucleotide located immediately 3′ tothe 5′-CAP of a mature mRNA typically corresponds to the transcriptionalstart site. The term “corresponds to” means that the 5′-UTR sequence maybe an RNA sequence, such as in the mRNA sequence used for defining the5′-UTR sequence, or a DNA sequence, which corresponds to such RNAsequence. In the context of the present invention, the term “a 5′-UTR ofa gene”, such as “a 5′-UTR of a TOP gene”, is the sequence, whichcorresponds to the 5′-UTR of the mature mRNA derived from this gene,i.e. the mRNA obtained by transcription of the gene and maturation ofthe pre-mature mRNA. The term “5′-UTR of a gene” encompasses the DNAsequence and the RNA sequence of the 5′-UTR. Preferably, the 5′-UTR usedaccording to the present invention is heterologous to the coding regionof the mRNA sequence. Even if 5′-UTR's derived from naturally occurringgenes are preferred, also synthetically engineered UTR's may be used inthe context of the present invention.3′-untranslated region (3′-UTR): In the context of the presentinvention, a 3′-UTR is typically the part of an mRNA, which is locatedbetween the protein coding region (i.e. the open reading frame) and the3′-terminus of the mRNA. A 3′-UTR of an mRNA is not translated into anamino acid sequence. The 3′-UTR sequence is generally encoded by thegene, which is transcribed into the respective mRNA during the geneexpression process. In the context of the present invention, a 3′-UTRcorresponds to the sequence of a mature mRNA, which is located 3′ to thestop codon of the protein coding region, preferably immediately 3′ tothe stop codon of the protein coding region, and which extends to the5′-side of the 3′-terminus of the mRNA or of the poly(A) sequence,preferably to the nucleotide immediately 5′ to the poly(A) sequence. Theterm “corresponds to” means that the 3′-UTR sequence may be an RNAsequence, such as in the mRNA sequence used for defining the 3′-UTRsequence, or a DNA sequence, which corresponds to such RNA sequence. Inthe context of the present invention, the term “a 3′-UTR of a gene”,such as “a 3′-UTR of an albumin gene”, is the sequence, whichcorresponds to the 3′-UTR of the mature mRNA derived from this gene,i.e. the mRNA obtained by transcription of the gene and maturation ofthe pre-mature mRNA. The term “3′-UTR of a gene” encompasses the DNAsequence and the RNA sequence of the 3′-UTR. Preferably, the 3′-UTR usedaccording to the present invention is heterologous to the coding regionof the mRNA sequence. Even if 3′-UTR's derived from naturally occurringgenes are preferred, also synthetically engineered UTR's may be used inthe context of the present invention.In vitro transcribed RNA: An in vitro transcribed RNA is an RNA moleculethat has been synthesized from a template DNA, commonly a linearized andpurified plasmid template DNA, a PCR product, or an oligonucleotide. RNAsynthesis occurs in a cell free (“in vitro”) assay catalyzed by DNAdependent RNA polymerases. In a process called RNA in vitrotranscription, virtually all nucleotides analogues into RNA. Particularexamples of DNA dependent RNA polymerases are the T7, T3, and SP6 RNApolymerases. An in vitro transcribed RNA may comprise elements such as5′-cap, optionally a 5′UTR, an open reading frame, optionally a 3′UTRand a poly(A) sequence. Aside from proteinogenic messenger RNA, severalnon-coding types of RNA exist which may be involved in regulation oftranscription and/or translation. Such All RNA molecules as definedherein may also be synthesized by RNA in vitro transcription.DNA: DNA is the usual abbreviation for deoxy-ribonucleic-acid. It is anucleic acid molecule, i.e. a polymer consisting of nucleotide monomers.These nucleotides are usually deoxy-adenosine-monophosphate,deoxy-thymidine-monophosphate, deoxy-guanosine-monophosphate anddeoxy-cytidine-monophosphate monomers which are—by themselves—composedof a sugar moiety (deoxyribose), a base moiety and a phosphate moiety,and polymerise by a characteristic backbone structure. The backbonestructure is, typically, formed by phosphodiester bonds between thesugar moiety of the nucleotide, i.e. deoxyribose, of a first and aphosphate moiety of a second, adjacent monomer. The specific order ofthe monomers, i.e. the order of the bases linked to thesugar/phosphate-backbone, is called the DNA-sequence. DNA may besingle-stranded or double-stranded. In the double stranded form, thenucleotides of the first strand typically hybridize with the nucleotidesof the second strand, e.g. by A/T-base-pairing and G/C-base-pairing.Cloning site, multiple cloning site: A cloning site is typicallyunderstood to be a segment of a nucleic acid molecule, which is suitablefor insertion of a nucleic acid sequence, e.g., a nucleic acid sequencecomprising an open reading frame. Insertion may be performed by anymolecular biological method known to the one skilled in the art, e.g. byrestriction and ligation. A cloning site typically comprises one or morerestriction enzyme recognition sites (restriction sites). These one ormore restrictions sites may be recognized by restriction enzymes whichcleave the DNA at these sites. A cloning site which comprises more thanone restriction site may also be termed a multiple cloning site (MCS) ora polylinker.Open reading frame: An open reading frame (ORF) in the context of theinvention may typically be a sequence of several nucleotide triplets,which may be translated into a peptide or protein. An open reading framepreferably contains a start codon, i.e. a combination of threesubsequent nucleotides coding usually for the amino acid methionine(ATG), at its 5′-end and a subsequent region, which usually exhibits alength which is a multiple of 3 nucleotides. An ORF is preferablyterminated by a stop-codon (e.g., TAA, TAG, TGA). Typically, this is theonly stop-codon of the open reading frame. Thus, an open reading framein the context of the present invention is preferably a nucleotidesequence, consisting of a number of nucleotides that may be divided bythree, which starts with a start codon (e.g. ATG) and which preferablyterminates with a stop codon (e.g., TAA, TGA, or TAG). The open readingframe may be isolated or it may be incorporated in a longer nucleic acidsequence, for example in a vector or an mRNA. An open reading frame mayalso be termed “protein coding region”.RNA in vitro transcription: The term “RNA in vitro transcription” (or‘in vitro transcription’) relates to a process wherein RNA, inparticular mRNA, is synthesized in a cell-free system (in vitro).Preferably, cloning vectors DNA, particularly plasmid DNA vectors areapplied as template for the generation of RNA transcripts. These cloningvectors are generally designated as transcription vector. RNA may beobtained by DNA dependent in vitro transcription of an appropriate DNAtemplate, which according to the present invention is preferably alinearized plasmid DNA template. The promoter for controlling RNA invitro transcription can be any promoter for any DNA dependent RNApolymerase. Particular examples of DNA dependent RNA polymerases are theT7, T3, and SP6 RNA polymerases. A DNA template for RNA in vitro RNAtranscription may be obtained by cloning of a nucleic acid, inparticular cDNA corresponding to the respective RNA to be in vitrotranscribed, and introducing it into an appropriate vector for RNA invitro transcription, for example in plasmid circular plasmid DNA. ThecDNA may be obtained by reverse transcription of mRNA or chemicalsynthesis. Moreover, the DNA template for in vitro RNA synthesis mayalso be obtained by gene synthesis. Preferably cloning vectors are usedfor RNA in vitro RNA transcription, which are generally designatedtranscription vectors.Transformation: In the context of the present invention, transformationcomprises the (non-viral) transfer of DNA, most commonly plasmid DNAinto competent bacteria. Common transformation techniques compriseheat-shock transformation of chemically competent bacteria (mostcommonly Escherichia coli) and electro-shock transformation of electrocompetent bacteria, commonly referred to as electroporation. Followingthat, transformed bacteria are selectively cultured in a suitable medium(e.g., LB-medium) containing antibiotics. The resistance against theantibiotics is transferred by the resistance gene, encoded by theplasmid.Polymerase chain reaction (PCR): The polymerase chain reaction (PCR) isa technology in molecular biology used to amplify a piece of DNA acrossseveral orders of magnitude, generating thousands to millions of copiesof a particular DNA sequence. Developed in 1983 by Kary Mullis(Bartlett, J. M. S.; Stirling, D. (2003). “A Short History of thePolymerase Chain Reaction”. PCR Protocols. Methods in Molecular Biology226 (2nd ed.). pp. 3-6) PCR is now a common and often indispensabletechnique used in medical and biological research labs for a variety ofapplications. The method relies on thermal cycling, consisting of cyclesof repeated heating and cooling of the reaction for DNA melting andenzymatic replication of the DNA. Primers (short DNA fragments)containing sequences complementary to the target sequence along with aheat-stable DNA polymerase, such as Taq polymerase, enable selective andrepeated amplification. As PCR progresses, the DNA generated is itselfused as a template for replication, setting in motion a chain reactionin which the DNA template is exponentially amplified. The DNA polymeraseenzymatically assembles a new DNA strand from DNA building-blocks, thenucleotides, by using single-stranded DNA as a template and DNAoligonucleotides (also called DNA primers), which are required forinitiation of DNA synthesis. The vast majority of PCR methods usethermal cycling, i.e., alternately heating and cooling the PCR samplethrough a defined series of temperature steps. In the first step, thetwo strands of the DNA double helix are physically separated at a hightemperature in a process called DNA melting. In the second step, thetemperature is lowered and the two DNA strands become templates for DNApolymerase to selectively amplify the target DNA. The selectivity of PCRresults from the use of primers that are complementary to the DNA regiontargeted for amplification under specific thermal cycling conditions.Quantitative Polymerase chain reaction (qPCR) or real-time polymerasechain reaction: A real-time polymerase chain reaction is a laboratorytechnique of molecular biology based on the polymerase chain reaction(PCR), which is used to amplify and simultaneously detect or quantify atargeted DNA molecule. The procedure follows the general principle ofpolymerase chain reaction (PCR); its key feature is that the amplifiedDNA is detected as the reaction progresses in “real time”. Two commonmethods for the detection of products in quantitative PCR are: (1)non-specific fluorescent dyes that intercalate with any double-strandedDNA, and (2) sequence-specific DNA probes consisting of oligonucleotidesthat are labelled with a fluorescent reporter, which permits detectiononly after hybridization of the probe with its complementary sequence toquantify nucleic acids. Quantitative PCR is carried out in a thermalcycler with the capacity to illuminate each sample with a beam of lightof a specified wavelength and detect the fluorescence emitted by theexcited fluorophore. The thermal cycler is also able to rapidly heat andchill samples, thereby taking advantage of the physicochemicalproperties of the nucleic acids and DNA polymerase. The PCR processgenerally consists of a series of temperature changes that are repeated25-40 times. These cycles normally consist of three stages: the first,at around 95° C., allows the separation of the nucleic acid's doublechain; the second, at a temperature of around 50-60° C., allows thebinding of the primers with the DNA template; the third, at between68-72° C., facilitates the polymerization carried out by the DNApolymerase. Due to the small size of the fragments the last step isusually omitted in this type of PCR as the enzyme is able to increasetheir number during the change between the alignment stage and thedenaturing stage. In addition, some thermal cyclers add another shorttemperature phase lasting only a few seconds to each cycle, with atemperature of, for example, 80° C., in order to reduce the noise causedby the presence of primer dimers when a non-specific dye is used. Thetemperatures and the timings used for each cycle depend on a widevariety of parameters, such as: the enzyme used to synthesize the DNA,the concentration of divalent ions and deoxyribonucleotides (dNTPs) inthe reaction and the bonding temperature of the primers. The type ofquantitative PCR technique used depends on the DNA sequence in thesamples, the technique can either use non-specific fluorochromes orhybridization probes.Quantitative PCR with double-stranded DNA-binding dyes as reporters: ADNA-binding dye such as SYBR Green binds to all double-stranded (ds) DNAin PCR, causing fluorescence of the dye. An increase in DNA productduring PCR therefore leads to an increase in fluorescence intensity andis measured at each cycle, thus allowing DNA concentrations to bequantified.1. The reaction is prepared as usual, with the addition of fluorescentdsDNA dye.2. The reaction is run in a quantitative PCR instrument, and after eachcycle, the levels of fluorescence are measured with a detector; the dyeonly fluoresces when bound to the dsDNA (i.e., the PCR product). Withreference to a standard dilution, the dsDNA concentration in the PCR canbe determined. Like other quantitative PCR methods, the values obtaineddo not have absolute units associated with them (i.e., mRNAcopies/cell). As described above, a comparison of a measured DNA/RNAsample to a standard dilution will only give a fraction or ratio of thesample relative to the standard, allowing only relative comparisonsbetween different samples.Fluorescent reporter probe method: Fluorescent reporter probes detectonly the DNA containing the probe sequence; therefore, use of thereporter probe significantly increases specificity, and enablesquantification even in the presence of non-specific DNA amplification.Fluorescent probes can be used in multiplex assays—for detection ofseveral genes in the same reaction—based on specific probes withdifferent-coloured labels, provided that all targeted genes areamplified with similar efficiency. The specificity of fluorescentreporter probes also prevents interference of measurements caused byprimer dimers, which are undesirable potential by-products in PCR. Themethod relies on a DNA-based probe with a fluorescent reporter at oneend and a quencher of fluorescence at the opposite end of the probe. Theclose proximity of the reporter to the quencher prevents detection ofits fluorescence; breakdown of the probe by the 5′ to 3′ exonucleaseactivity of the Taq polymerase breaks the reporter-quencher proximityand thus allows unquenched emission of fluorescence, which can bedetected after excitation with a laser. An increase in the producttargeted by the reporter probe at each PCR cycle therefore causes aproportional increase in fluorescence due to the breakdown of the probeand release of the reporter.1. The PCR is prepared as usual (see PCR), and the reporter probe isadded.2. As the reaction commences, during the annealing stage of the PCR bothprobe and primers anneal to the DNA target.3. Polymerisation of a new DNA strand is initiated from the primers, andonce the polymerase reaches the probe, its 5′-3′-exonuclease degradesthe probe, physically separating the fluorescent reporter from thequencher, resulting in an increase in fluorescence.4. Fluorescence is detected and measured in a real-time PCR machine, andits geometric increase corresponding to exponential increase of theproduct is used to determine the quantification cycle (Cq) in eachreaction.Ligation, DNA ligation: Ligation in molecular biology is the joining oftwo nucleic acid fragments through the action of an enzyme. It is anessential laboratory procedure in the molecular cloning of DNA wherebyDNA fragments are joined together to create recombinant DNA molecules,such as when a foreign DNA fragment is inserted into a plasmid. The endsof DNA fragments are joined together by the formation of phosphodiesterbonds between the 3′-hydroxyl of one DNA terminus with the 5′-phosphorylof another. Ligation in the laboratory is normally performed using T4DNA ligase, however, procedures for ligation without the use of standardDNA ligase are also popular.Kozak sequence: As used herein, the term ‘Kozak sequence’ typicallyrefers to a sequence on an mRNA molecule, which is recognized by theribosome as the translational start site of a protein encoded by thatmRNA molecule. In a preferred embodiment, that sequence may comply witha consensus sequence for a nucleotide sequence mediating initiation oftranslation, preferably with the consensus sequence (gcc)gccRccAUGG (SEQID NO: 20), wherein a lower case letter denotes the most common base ata position where the base can nevertheless vary; upper case lettersindicate highly conserved bases, ‘AUGG’; ‘R’ indicates that a purine(adenine or guanine, preferably adenine) is present at this position;and the sequence in brackets is of uncertain significance.HPLC: High-performance liquid chromatography (HPLC; formerly referred toas high-pressure liquid chromatography), is a technique in analyticchemistry used to separate the components in a mixture, to identify eachcomponent, and to quantify each component. It relies on pumps to pass apressurized liquid solvent containing the sample mixture through acolumn filled with a solid adsorbent material. Each component in thesample interacts slightly differently with the adsorbent material,causing different flow rates for the different components and leading tothe separation of the components as they flow out the column. HPLC isdistinguished from traditional (“low pressure”) liquid chromatographybecause operational pressures are significantly higher (50-350 bar),while ordinary liquid chromatography typically relies on the force ofgravity to pass the mobile phase through the column. Due to the smallsample amount separated in analytical HPLC, typical column dimensionsare 2.1-4.6 mm diameter, and 30-250 mm length. Also HPLC columns aremade with smaller sorbent particles (2-50 micrometer in average particlesize). This gives HPLC superior resolving power when separatingmixtures, which is why it is a popular chromatographic technique. Theschematic of an HPLC instrument typically includes a sampler, pumps, anda detector. The sampler brings the sample mixture into the mobile phasestream which carries it into the column. The pumps deliver the desiredflow and composition of the mobile phase through the column. Thedetector generates a signal proportional to the amount of samplecomponent emerging from the column, hence allowing for quantitativeanalysis of the sample components. A digital microprocessor and usersoftware control the HPLC instrument and provide data analysis. Somemodels of mechanical pumps in a HPLC instrument can mix multiplesolvents together in ratios changing in time, generating a compositiongradient in the mobile phase. Various detectors are in common use, suchas UV/Vis, photodiode array (PDA) or based on mass spectrometry. MostHPLC instruments also have a column oven that allows for adjusting thetemperature the separation is performed at.Endotoxin: Endoxins are lipopolysaccharides (LPS), also known aslipoglycans, which are large molecules consisting of a lipid and apolysaccharide composed of O-antigen, outer core and inner core joinedby a covalent bond; they are found in the outer membrane ofGram-negative bacteria, and elicit strong immune responses in animals.

It comprises three parts:

1. O antigen (or O polysaccharide)

2. Core oligosaccharide

3. Lipid A

O-antigen: A repetitive glycan polymer contained within an LPS isreferred to as the O antigen, O polysaccharide, or O side-chain of thebacteria. The O antigen is attached to the core oligosaccharide, andcomprises the outermost domain of the LPS molecule. The composition ofthe O chain varies from strain to strain.Core oligosaccharide: The Core domain always contains an oligosaccharidecomponent that attaches directly to lipid A and commonly contains sugarssuch as heptose and 3-deoxy-D-mannooctulosonic Acid (also known as KDO,keto-deoxyoctulosonate). The LPS Cores of many bacteria also containnon-carbohydrate components, such as phosphate, amino acids, andethanolamine substituents.Lipid A:

Lipid A is, in normal circumstances, a phosphorylated glucosaminedisaccharide decorated with multiple fatty acids. These hydrophobicfatty acid chains anchor the LPS into the bacterial membrane, and therest of the LPS projects from the cell surface. The lipid A domain isresponsible for much of the toxicity of Gram-negative bacteria. Whenbacterial cells are lysed by the immune system, fragments of membranecontaining lipid A are released into the circulation, causing fever,diarrhea, and possible fatal endotoxic shock (also called septic shock).The Lipid A moiety is a very conserved component of the LPS.

Pyrogen: A pyrogen is a substance that induces fever. These can beeither internal (endogenous) or external (exogenous) to the body. Thebacterial substance lipopolysaccharide (LPS), present in the cell wallof some bacteria, is an example of an exogenous pyrogen.Bioburden: As defined herein, the term ‘bioburden’ typically relates tothe number of bacteria, which are present in a given sample, such as theproduct RNA or an intermediate product of the method according to theinvention. In preferred embodiments, the bioburden is determined by anysuitable method known in the art, preferably by using a method asdescribed in PhEur 2.6.12.Lyophilization: Freeze-drying, also known as lyophilization, orcryodesiccation, is a dehydration process typically used to preserve aperishable material or make the material more convenient for transport.Freeze-drying works by freezing the material and then reducing thesurrounding pressure to allow the frozen water in the material tosublimate directly from the solid phase to the gas phase.DNA Sequencing: DNA sequencing is the process of determining the preciseorder of nucleotides within a DNA molecule. It includes any method ortechnology that is used to determine the order of the fourbases—adenine, guanine, cytosine, and thymine—in a strand of DNA. Itincludes Maxam-Gilbert sequencing, Sanger sequencing (chain-terminationsequencing), next generation sequencing, cycle sequencing, capillaryelectrophoresis DNA sequencing, single-molecule real-time sequencing,Ion Torrent sequencing, pyrosequencing, sequencing by synthesis,sequencing by ligation.RNA Sequencing: In order to sequence RNA, the usual method is first toreverse transcribe the sample to generate cDNA fragments. This can thenbe sequenced as described above for DNA Sequencing.Reverse Transcriptase: A Reverse transcriptase (RT) is an enzyme used togenerate complementary DNA (cDNA) from an RNA template, a process termedreverse transcription. It is mainly associated with retroviruses.Retroviral RT has three sequential biochemical activities: RNA-dependentDNA polymerase activity, ribonuclease H, and DNA-dependent DNApolymerase activity.Reverse Transcription: Reverse transcription is the process ofgenerating a complementary DNA form an RNA template by a reversetranscriptase.RT-PCR (Reverse transcription polymerase chain reaction): In RT-PCR, theRNA template is first converted into a complementary DNA (cDNA) using areverse transcriptase. The cDNA is then used as a template forexponential amplification using PCR.RNA polymerase/DNA-dependent RNA polymerase: RNA polymerase (RNAP orRNApol), also known as DNA-dependent RNA polymerase, is an enzyme thatproduces primary transcript RNA. In cells, RNAP is necessary forconstructing RNA chains using DNA genes as templates, a process calledtranscription. RNA polymerase enzymes are essential to life and arefound in all organisms and many viruses. In chemical terms, RNAP is anucleotidyl transferase that polymerizes ribonucleotides at the 3′ endof an RNA transcript. Particularly preferred in the context of thepresent invention are T3, T7 and Sp6 RNA polymerases. FIG. 2 showsconsensus promoter sequences. The +1 base is the first base incorporatedinto RNA during transcription. The underline indicates the minimumsequence required for efficient transcription.

In one aspect, the present invention relates to a method for producingRNA comprising the following steps:

a) providing a template DNA comprising a nucleic acid sequence encodingan RNA sequence;

b) in vitro transcription of the template DNA in order to obtain acomposition comprising the RNA;

wherein the method comprises

at least one step for controlling the quality of the template DNAprovided in step a),

wherein the at least one step for controlling the quality of thetemplate DNA comprises at least one selected from the group consistingof determining the concentration of the template DNA in a sample,determining the integrity of the template DNA, determining the identityof the template DNA, and determining the purity of the template DNA;and/orat least one step for controlling the quality of the RNA obtained instep b),wherein the at least one step for controlling the quality of the RNAobtained in step b) comprises at least one step selected from the groupconsisting of determining the concentration of the RNA in a sample,determining the integrity of the RNA, determining the identity of theRNA, determining the purity of the RNA, determining the pH of a samplecomprising the RNA, determining the osmolality of a sample comprisingthe RNA, determining the presence and/or the amount of the template DNAin a sample comprising the RNA, and determining the presence and/or theamount of an organic solvent in a sample comprising the RNA.

According to the invention, the concentration of the template DNA in asample, the integrity of the template DNA, the identity of the templateDNA, preferably the identity of the nucleic acid sequence encoding anRNA sequence, and/or the purity of the template DNA may be determined byany method known in the art. The template DNA is preferably provided instep a) in the form of a liquid composition comprising the template DNAas defined herein. Typically, a (liquid) sample will be taken for eachstep of quality control. Such sample preferably represents the qualityof the template DNA provided in step a). More preferably, such a sampleis used for the quality control without further manipulation (e.g.undiluted). Alternatively, a sample may be further processed in order toperform the respective quality control. In a preferred embodiment, theat least one step for controlling the quality of the template DNAcomprises a method as described herein, preferably as described hereinwith respect to methods suitable to be used as quality control oftemplate DNA. In a particularly preferred embodiment, the at least onestep for controlling the quality of the template DNA is as describedherein, preferably a step as described herein under section ‘A. QualityControl 1’. In this context, the expression ‘controlling the quality ofthe template DNA’ may refer to a quality control carried out using the(final) product of step a) (i.e. the template DNA comprising a nucleicacid sequence encoding an RNA sequence, which is used as template instep b) of the inventive method), and/or any intermediate productprovided in step a) of the method (e.g. a fragment of the template DNA).In a preferred embodiment the quality of the template DNA is controlledat least at two different stages of step a), wherein preferably at leastone quality control is carried out using an intermediate DNA product andat least one quality control is carried out using the final product ofstep a), i.e. the template DNA comprising a nucleic acid sequenceencoding an RNA sequence.

In a preferred embodiment, the concentration of the template DNAprovided in step a) is determined by photometric measurement, preferablyas described herein.

In a further embodiment of the inventive method, the identity of thetemplate DNA provided in step a) is determined in order to control thequality of the template DNA. In this context, it is preferred that theidentity of the nucleic acid sequence encoding the RNA sequence, isdetermined. Any suitable method for directly or indirectly determiningthe identity of a nucleic acid molecule may be used. Preferably, theidentity of the template DNA, more preferably of the nucleic acidsequence encoding the RNA, is determined by using at least one stepselected from polymerase chain reaction (PCR), restriction analysis orsequence analysis, preferably as described herein.

In a preferred embodiment, the inventive method comprises determiningthe purity of the template DNA provided in step a). More preferably, thepurity of the template DNA provided in step a) is determined bydetermining in a sample comprising the template DNA the presence and/orthe amount of RNA; the presence and/or the amount of protein; thepresence and/or the amount of endotoxin; the presence and/or the amountof bacterial DNA; and/or the presence and/or the amount of ribonuclease.According to an embodiment of the present invention, the presence of anRNA, a protein, an endotoxin, a bacterial DNA, and/or ribonuclease maybe determined in a qualitative manner. More preferably, such impuritiesare quantified by using suitable quantitative methods in order todetermine the respective amounts.

For instance, the presence and/or the amount of bacterial DNA in asample comprising the template DNA provided in step a) may be determinedby using a polymerase chain reaction (PCR) method. In order to determinethe amount of bacterial DNA in a sample comprising the template DNA,quantitative PCR methods, preferably as described herein, are preferablyused. Depending on the primer pair, which is employed in such a PCRbased method, different bacterial DNA sequences may be amplified anddetected.

In a preferred embodiment, the presence and/or the amount of bacterialDNA is determined by using an universal primer pair for bacterial DNA.In that embodiment, the primers are preferably designed in order toamplify universally occurring bacterial DNA. By using such an approach,the general bioburden of the template DNA is preferably determined.

Alternatively, a PCR based method may be used in order to determine thepresence and/or the amount of a specific microbial agent, such as aspecific bacterial strain. In that embodiment, primer pairs arepreferably used having a high specificity for DNA from a certainorganism. As an alternative, an universal primer pair for bacterial DNAmay be employed. In a preferred embodiment of the invention, thepresence and/or the amount of E. coli DNA is determined using a primerpair specific for E. coli DNA. Preferably, a primer pair is used that issuitable for amplifying the E. coli uidA gene. This embodiment isparticularly preferred if E. coli is used for DNA templateamplification.

As explained above with respect to the at least one step for controllingthe quality of the template DNA, also the at least one step forcontrolling the quality of the RNA obtained in step b) may be anysuitable method known in the art. According to the inventive method, anymethod may be used in the at least one step for controlling the qualityof the RNA obtained in step b). Preferably, the at least one step forcontrolling the quality of the RNA obtained in step b) comprises atleast one step selected from determining the concentration of the RNA ina sample, determining the integrity of the RNA, determining the identityof the RNA, determining the purity of the RNA, determining the pH of asample comprising the RNA, determining the osmolality of a samplecomprising the RNA, determining the presence and/or the amount of thetemplate DNA in a sample comprising the RNA, and determining thepresence and/or the amount of an organic solvent in a sample comprisingthe RNA, wherein the at least one step is a step as described herein. Ina particularly preferred embodiment, the inventive method comprisescontrolling the quality of the RNA obtained in step b) by determiningthe concentration of the RNA in a sample, determining the integrity ofthe RNA, determining the identity of the RNA, determining the purity ofthe RNA, determining the pH of a sample comprising the RNA, determiningthe osmolality of a sample comprising the RNA, determining the presenceand/or the amount of the template DNA in a sample comprising the RNA,and determining the presence and/or the amount of an organic solvent ina sample comprising the RNA. In a particularly preferred embodiment, theat least one step for controlling the quality of the RNA obtained instep b) is a step as described herein, preferably a step as describedherein under section ‘B. Quality Control 2’.

The at least one step for controlling the quality of the RNA obtained instep b) is typically carried out in a sample, which is taken from thecomposition comprising the RNA. In a preferred embodiment, the sample isa liquid sample. In one embodiment, the sample may be taken from theproduction batch without further processing it. Alternatively, a samplecomprising the RNA obtained in step b) may be processed before thequality control. This applies in particular, if a step for qualitycontrol is carried out at a stage of the process, where the RNA in theproduction batch is present in solid form (e.g. after precipitation orlyophilization). In one preferred embodiment, a sample may thereforecomprise RNA that has been resuspended in a suitable solvent (e.g. waterfor injection).

As used herein, the expression ‘controlling the quality of the RNAobtained in step b)’ may refer to a quality control carried out usingthe final RNA product (e.g. a purified RNA as described herein) obtainedby the inventive method. Furthermore, the expression ‘controlling thequality of the RNA obtained in step b)’ may also refer to a qualitycontrol carried out using any intermediate RNA product obtained in stepb) of the inventive method (e.g. the raw RNA product in the (terminated)in vitro transcription batch). In a preferred embodiment of theinventive method, the quality of the RNA is controlled at least at twostages of step b) of the method, wherein preferably at least in onestage the quality of an intermediate RNA product is controlled and atleast in one further stage the quality of the final RNA product iscontrolled.

According to an embodiment of the invention, the method comprises a stepof determining by photometric measurement the concentration of the RNAobtained in step b), preferably as described herein.

The inventive method may further comprise at least one step forcontrolling the quality of the RNA obtained in step b), wherein theintegrity of the RNA obtained in step b) is determined by determiningthe integrity of the RNA e.g. by determining the percentage offull-length RNA, preferably as described herein.

According to the invention, the at least one step for controlling thequality of the RNA obtained in step b) preferably comprises determiningthe identity of the RNA obtained in step b) by determining the length ofthe RNA; by digesting the RNA with a ribonuclease; by determining thelength of a cDNA obtained by RT-PCR using the RNA as a template; byoligonucleotide mapping; by determining the sequence of the RNA by RNAsequencing; and/or by determining the sequence of a cDNA obtained by RTor RT-PCR using the RNA as a template.

Further preferably, the inventive method comprises determining thepurity of the RNA obtained in step b) by determining in a samplecomprising the RNA the presence and/or the amount of protein; thepresence and/or the amount of endotoxin; the presence and/or the amountof bacterial DNA; the presence and/or the amount of plasmid DNA; and/orthe presence and/or the amount of organic solvent. According to oneembodiment, the presence of a protein, an endotoxin, a bacterial DNA, aplasmid DNA and/or an organic solvent may be determined in a qualitativemanner. More preferably, such impurities are quantified by usingsuitable quantitative methods in order to determine the respectiveamounts. For example, the presence and/or the amount of bacterial DNA ina sample comprising the RNA obtained in step b) may be determined byusing a PCR method. As described above with respect to a step forcontrolling the quality of the template DNA, the presence and/or theamount of bacterial DNA can be determined by using an universal primerpair for bacterial DNA. Alternatively, a primer pair specific for E.coli DNA may be used in order to determine the presence and/or theamount of E. coli DNA in a sample comprising the RNA obtained in step b)of the inventive method. Preferably, a primer pair specific for the E.coli uidA gene is used. This embodiment is particularly preferred if E.coli is used for DNA template amplification.

In addition or alternatively to any of the steps described above, the pHand/or the osmolality of a sample comprising the RNA obtained in step b)may be determined. The respective values of the sample are preferably inthe ranges as defined herein.

According to the inventive method, step a) may also comprise a step ofselecting an RNA sequence. Preferably, the selected RNA sequence is anRNA sequence, which encodes a protein or a fragment or variant thereof,preferably as described herein. In a preferred embodiment, an mRNAsequence is selected in step a) of the method. In that embodiment, thetemplate DNA comprises a nucleic acid sequence encoding an mRNA.Alternatively, the selected RNA may be any other type of RNA or an RNAas defined herein, preferably a small interfering RNA (siRNA), anantisense RNA, a CRISPR RNA, a ribozyme, an aptamer, a riboswitch, animmunostimulating RNA, a transfer RNA (tRNA), a ribosomal RNA (rRNA), asmall nuclear RNA (snRNA), a small nucleolar RNA (snoRNA), a microRNA(miRNA), or a Piwi-interacting RNA (piRNA).

According to a preferred embodiment, step a) comprises synthesis of thetemplate DNA, wherein the synthesis of the template DNA or a fragmentthereof comprises a step of reverse transcription (RT), more preferablya step of RT-PCR. Preferably, the selected RNA sequence is used as atemplate in a step of RT-PCR. By using RT or RT-PCR, respectively, cDNAcan be synthesized, which corresponds to the selected RNA sequence or afragment thereof.

In addition or alternatively, the template DNA or a fragment thereof maybe synthesized chemically in step a) of the inventive method.

In a preferred embodiment, the synthesis of the template DNA comprisesligating at least two DNA fragments, preferably as described herein,wherein each of the DNA fragments comprises a nucleic acid sequenceencoding a fragment of the selected RNA sequence.

According to an embodiment of the invention, the template DNA is a DNAplasmid, preferably a circular DNA plasmid comprising a bacterial originof replication and a selection marker. Such a plasmid DNA is typicallyproduced in bacteria. Preferably, the plasmid DNA (which—in thisembodiment—is the template DNA) is transformed into bacteria, thebacteria are cultured under selective conditions and the plasmid DNA isisolated from the bacteria.

In order to control the quality of the template DNA, at least one stepof controlling the quality of the template DNA is preferably carried outafter isolation from the bacteria by at least one step selected fromphotometrically determining the concentration of the template DNA in asample; determining the presence and/or the amount of RNA contamination;determining the identity of the template DNA by restriction analysis;determining the identity of the template DNA by sequence analysis;determining the presence and/or the amount of endotoxin; determining thepresence and/or the amount of protein; determining the bioburden;determining the presence and/or the amount of bacterial DNA; anddetermining the presence and/or the amount of E. coli DNA. Morepreferably, the quality of the template DNA is controlled afterisolation from the bacteria by using all of the above steps incombination. All of the above steps may be used sequentially, so thatcertain quality control steps are applied after a certain step in themethod and all of the above quality control steps are used over theentire method. Alternatively, all of the above quality control steps areused in combination in order to control the quality of the template DNAat a certain stage or at each of the stages of the inventive method.According to a particularly preferred embodiment, the quality of thetemplate DNA is controlled at a certain stage of the method, preferablyafter isolation of the template DNA from bacteria after cultivation ofthe bacteria by photometrically determining the concentration of thetemplate DNA in a sample; determining the presence and/or the amount ofRNA contamination; determining the identity of the template DNA byrestriction analysis; determining the identity of the template DNA bysequence analysis; determining the presence and/or the amount ofendotoxin; determining the presence and/or the amount of protein;determining the bioburden; determining the presence and/or the amount ofbacterial DNA; and determining the presence and/or the amount of E. coliDNA. In a particularly preferred embodiment, the quality of the templateDNA is controlled after isolation of the template DNA from bacteriaafter cultivation of the bacteria by at least one step as describedherein, preferably a step as described herein under section ‘A. QualityControl 1’.

According to an embodiment of the invention, step a) compriseslinearization of the template DNA, in particular where the template DNAis a circular molecule, such as a DNA plasmid.

The quality of the template DNA may also be controlled, preferably afterlinearization of the template DNA, by at least one step selected fromthe group consisting of controlling the linearization; estimating RNAyield in an in vitro transcription reaction; determining the identity ofan RNA obtained in an in vitro transcription reaction; and determining aribonuclease contamination. A single one of the above steps or all ofthe above steps may be used sequentially, so that certain qualitycontrol steps are applied after a certain step in the method and all ofthe above quality control steps are used over the entire method.Alternatively, all of the above quality control steps are used incombination in order to control the quality of the template DNA at acertain stage or at each of the stages of the inventive method It isparticularly preferred in this embodiment, that all of the steps aboveare used in combination. Preferably, the quality of the template DNA iscontrolled at at least one stage of the method, preferably afterlinearization of the template DNA, by controlling the linearization;estimating RNA yield in an in vitro transcription reaction; determiningthe identity of an RNA obtained in an in vitro transcription reaction;and determining a ribonuclease contamination.

According to the inventive method, step b) comprises an in vitrotranscription reaction. Without any limitation, this reaction may becarried out as known in the art. Preferably, the in vitro transcriptionof step b) of the inventive method is carried out in presence ofnaturally occurring nucleotides. Alternatively, the in vitrotranscription may also be carried out by using modified nucleotides,preferably as defined herein. In a particularly preferred embodiment,the in vitro transcription reaction is performed in presence ofnaturally occurring and modified nucleotides.

In a preferred embodiment, the RNA obtained in step b) is a capped RNA,preferably a co-transcriptionally capped RNA.

It is further preferred that the in vitro transcription in step b) iscarried out in presence of a cap analog. The cap analog is preferablyselected from the group consisting of N7-MeGpppG (=m7G(5′)ppp(5′)G),m7G(5′)ppp(5′)A, ARCA (anti-reverse CAP analogue, modified ARCA (e.g.phosphothioate modified ARCA), inosine, N1-methyl-guanosine,2′-fluoro-guanosine, 7-deaza-guanosine, 8-oxo-guanosine,2-amino-guanosine, LNA-guanosine, and 2-azido-guanosine.

In a particularly preferred embodiment of the inventive method, the invitro transcription in step b) is carried out in presence of a capanalog, GTP, ATP, CTP and UTP, wherein the amount of GTP is reduced withrespect to the amounts of ATP, CTP and UTP. In that embodiment, ATP, CTPand UTP are preferably present in equal amounts. The ratio of the capanalog to GTP is preferably in a range from 10:1 to 1:1.

The in vitro transcription in step b) is preferably carried out inpresence of a DNA dependent RNA polymerase, which is preferably selectedfrom the group consisting of T3 RNA polymerase, T7 RNA polymerase andSP6 RNA polymerase.

In a preferred embodiment, the RNA obtained in step b) is anenzymatically capped RNA. In that embodiment, step b) comprises a stepof enzymatically capping the RNA, preferably as described herein.

In some embodiments, the RNA obtained in step b) comprises a poly(A)sequence. Preferably, the RNA obtained in step b) is polyadenylated in astep of enzymatic polyadenylation, wherein the enzyme is preferably abacterial poly(A) polymerase.

According to a particularly preferred embodiment of the inventivemethod, the RNA obtained in step b) is purified by at least onepurification step in order to obtain purified RNA. The RNA obtained bythe in vitro transcription reaction in step b) may optionally bepurified by any suitable purification step known in the art or by anycombination of such steps. Preferred purification steps include methodsfor purification compatible with RNA, in particular methods that do notmodify the identity of the RNA or that do not have a negative impact onthe integrity of the RNA. Further preferred are purification steps,which are compatible with subsequent clinical use of the RNA product.

In a preferred embodiment, the inventive method comprises at least onepurification step, which comprises at least one selected from the groupconsisting of a precipitation step and a chromatographic step. Theprecipitation step is preferably an alcoholic precipitation step or aLiCl precipitation step. The chromatographic step is preferably selectedfrom the group consisting of HPLC, preferably RP-HPLC, anion exchangechromatography, affinity chromatography, hydroxyapatite chromatographyand core bead chromatography.

In particularly preferred embodiments, the RNA obtained in step b) ispurified by at least one first and at least one second purificationstep. The at least one first and at least one second purification stepmay be the same or different. In certain embodiments, the samepurification step may be carried out more than once. In a particularlypreferred embodiment, different purification steps are combined witheach other, typically by carrying out one purification step afteranother one. Preferably, the at least one first purification step iscarried out prior to the at least one second purification step.

According to a preferred embodiment of the present invention, the atleast one first purification step comprises a precipitation step and theat least one second purification step comprises a chromatographic step.Without being bound by any theory, it is believed that the combinationof a precipitation step and a chromatographic step is particularlyuseful for obtaining purified RNA. In that embodiment, it is furtherpreferred that the at least one first purification step comprises analcohol precipitation step or a LiCl precipitation step and that the atleast one second purification step comprises a chromatographic stepselected from the group consisting of HPLC, preferably RP-HPLC, anionexchange chromatography, affinity chromatography, hydroxyapatitechromatography and core bead chromatography. Most preferably, the atleast one first purification step comprises a LiCl precipitation stepand the at least one second purification step comprises a step ofRP-HPLC.

According to preferred embodiments of the invention, the methodcomprises at least one step for controlling the quality of the purifiedRNA. In this respect, reference is made to the description of the atleast one step for controlling quality of the RNA obtained in step b).The steps described herein in this respect equally apply to a purifiedRNA obtained after an optional purification step as described herein. Itis particularly preferred that the quality of the purified RNA iscontrolled by at least one step as described herein, preferably a stepas described herein under section ‘B. Quality Control 2’. It ispreferred that the success of the at least one optional purificationstep is controlled by applying at least one step for controlling thequality of the RNA, preferably as defined herein. More preferably, thequality of the purified RNA is controlled after the at least onepurification step by at least one step selected from determining theidentity of the purified RNA and determining the integrity of thepurified RNA.

In embodiments comprising more than one purification step it ispreferred that the success of each of the steps is controlledindividually by using at least one step for controlling the quality ofthe RNA as described herein. More preferably, the quality of thepurified RNA is controlled after the at least one first purificationstep and after the at least one second purification step by at least onestep selected from determining the identity of the purified RNA anddetermining the integrity of the purified RNA. The identity of thepurified RNA and/or the integrity of the purified RNA are preferablydetermined by gel electrophoresis, more preferably as described herein.

The RNA obtained in step b), such as the purified RNA as describedherein, may further be dried by any suitable method. Preferably, thecomposition comprising the RNA obtained in step b) or a compositioncomprising the purified RNA obtained by the inventive method includingat least one optional purification step is lyophilized.

According to a particularly preferred embodiment, the quality of the RNAobtained in step b) or the quality of the purified RNA is controlled byat least one step selected from the group consisting of determining theidentity of the RNA by digesting the RNA with a ribonuclease;determining the identity of the RNA by using RT or RT-PCR; determiningthe identity and/or the integrity of the RNA by gel electrophoresis;determining the pH of a sample comprising the RNA; determining theosmolality of a sample comprising the RNA; determining the bioburden;determining the presence and/or the amount of endotoxin; determining thepresence and/or amount of protein; determining the presence and/oramount of the template DNA; determining the presence and/or the amountof bacterial DNA; and determining the presence and/or the amounts oforganic solvent. It is further particularly preferred that the qualityof the RNA is controlled by combining all of the above steps. Forinstance, the steps above may be applied sequentially by applying one ormore of these quality control steps after a certain step in the methodfor producing RNA, preferably after a certain step following the invitro transcription in step b) of the inventive method, so that all ofthese steps are used (at different stages) in the inventive method forproducing RNA. Alternatively, all of these steps may be carried out incombination after certain steps in the inventive method or after eachstep of the inventive method, preferably after the in vitrotranscription in step b) of the inventive method or after at least oneoptional purification step. In a particularly preferred embodiment ofthe invention, the quality of the RNA obtained in step b) or the qualityof the purified RNA is controlled by determining the identity of the RNAby digesting the RNA with a ribonuclease; determining the identity ofthe RNA by using RT or RT-PCR; determining the identity and/or theintegrity of the RNA by gel electrophoresis; determining the pH of asample comprising the RNA; determining the osmolality of a samplecomprising the RNA; determining the bioburden; determining the presenceand/or the amount of endotoxin; determining the presence and/or amountof protein; determining the presence and/or amount of the template DNA;determining the presence and/or the amount of bacterial DNA; anddetermining the presence and/or the amounts of organic solvent.

According to a preferred embodiment, step a) of the inventive methodcomprises the selection of an RNA sequence. The selected RNA sequenceselected typically comprises an RNA sequence, which corresponds to anRNA molecule, which is produced by the inventive method. The selectedRNA sequence may be a coding RNA, which encodes a protein sequence or afragment or variant thereof (e.g. fusion proteins), preferably selectedfrom therapeutically active proteins or peptides, including adjuvantproteins, tumor antigens, pathogenic antigens (e.g. selected, fromanimal antigens, from viral antigens, from protozoal antigens, frombacterial antigens), allergenic antigens, autoimmune antigens, orfurther antigens, from allergens, from antibodies, fromimmunostimulatory proteins or peptides, from antigen-specific T-cellreceptors, biologies, cell penetrating peptides, secreted proteins,plasma membrane proteins, cytoplasmic or cytoskeletal proteins,intracellular membrane bound proteins, nuclear proteins, proteinsassociated with human disease, targeting moieties or those proteinsencoded by the human genome, for which no therapeutic indication hasbeen identified but which nonetheless have utility in areas of researchand discovery. The coding RNAs may be e.g. mRNAs, viral RNAs, orreplicon RNAs.

Alternatively, the selected RNA sequence may be any further RNA asdefined herein, particularly a small interfering RNA (siRNA), anantisense RNA, a CRISPR RNA, a ribozyme, an aptamer, a riboswitch, animmunostimulating RNA, a transfer RNA (tRNA), a ribosomal RNA (rRNA), asmall nuclear RNA (snRNA), a small nucleolar RNA (snoRNA), a microRNA(miRNA), or a Piwi-interacting RNA (piRNA).

If the target RNA sequence that is selected encodes a peptide or aprotein, the coding sequence may be readily identified by one of skillin the art by using public and private databases, e.g. GenBank.

In preferred embodiments, the RNA produced by the inventive methodcomprises naturally occurring and/or modified nucleotides. Severalmodifications are known in the art, which can be applied to a nucleotidecomprised in the RNA obtained by using the inventive method. In apreferred embodiment, the invention thus provides a method for providinga modified RNA, preferably as defined herein, more preferably an RNAcomprising at least one modification as described herein.

Chemical Modifications:

The term “RNA modification” as used herein may refer to chemicalmodifications comprising backbone modifications as well as sugarmodifications or base modifications.

In this context, a modified RNA molecule as defined herein may containnucleotide analogues/modifications, e.g. backbone modifications, sugarmodifications or base modifications. A backbone modification inconnection with the present invention is a modification, in whichphosphates of the backbone of the nucleotides contained in an RNAmolecule as defined herein are chemically modified. A sugar modificationin connection with the present invention is a chemical modification ofthe sugar of the nucleotides of the RNA molecule as defined herein.Furthermore, a base modification in connection with the presentinvention is a chemical modification of the base moiety of thenucleotides of the RNA molecule. In this context, nucleotide analoguesor modifications are preferably selected from nucleotide analogues,which are applicable for transcription and/or translation.

Sugar Modifications:

The modified nucleosides and nucleotides, which may be incorporated intoa modified RNA molecule as described herein, can be modified in thesugar moiety. For example, the 2′ hydroxyl group (OH) can be modified orreplaced with a number of different “oxy” or “deoxy” substituents.Examples of “oxy”-2′ hydroxyl group modifications include, but are notlimited to, alkoxy or aryloxy (—OR, e.g., R═H, alkyl, cycloalkyl, aryl,aralkyl, heteroaryl or sugar); polyethyleneglycols (PEG),—O(CH₂CH₂O)nCH₂CH₂OR; “locked” nucleic acids (LNA) in which the 2′hydroxyl is connected, e.g., by a methylene bridge, to the 4′ carbon ofthe same ribose sugar; and amino groups (—O-amino, wherein the aminogroup, e.g., NRR, can be alkylamino, dialkylamino, heterocyclyl,arylamino, diarylamino, heteroarylamino, or diheteroaryl amino, ethylenediamine, polyamino) or aminoalkoxy.

“Deoxy” modifications include hydrogen, amino (e.g. NH2; alkylamino,dialkylamino, heterocyclyl, arylamino, diaryl amino, heteroaryl amino,diheteroaryl amino, or amino acid); or the amino group can be attachedto the sugar through a linker, wherein the linker comprises one or moreof the atoms C, N, and O.

The sugar group can also contain one or more carbons that possess theopposite stereochemical configuration than that of the correspondingcarbon in ribose. Thus, a modified RNA molecule can include nucleotidescontaining, for instance, arabinose as the sugar.

Backbone Modifications:

The phosphate backbone may further be modified in the modifiednucleosides and nucleotides, which may be incorporated into a modifiedRNA molecule as described herein. The phosphate groups of the backbonecan be modified by replacing one or more of the oxygen atoms with adifferent substituent. Further, the modified nucleosides and nucleotidescan include the full replacement of an unmodified phosphate moiety witha modified phosphate as described herein. Examples of modified phosphategroups include, but are not limited to, phosphorothioate,phosphoroselenates, borano phosphates, borano phosphate esters, hydrogenphosphonates, phosphoroamidates, alkyl or aryl phosphonates andphosphotriesters. Phosphorodithioates have both non-linking oxygensreplaced by sulfur. The phosphate linker can also be modified by thereplacement of a linking oxygen with nitrogen (bridgedphosphoroamidates), sulfur (bridged phosphorothioates) and carbon(bridged methylene-phosphonates).

Base Modifications:

The modified nucleosides and nucleotides, which may be incorporated intoa modified RNA molecule as described herein can further be modified inthe nucleobase moiety. Examples of nucleobases found in RNA include, butare not limited to, adenine, guanine, cytosine and uracil. For example,the nucleosides and nucleotides described herein can be chemicallymodified on the major groove face. In some embodiments, the major groovechemical modifications can include an amino group, a thiol group, analkyl group, or a halo group.

In particularly preferred embodiments of the present invention, thenucleotide analogues/modifications are selected from base modifications,which are preferably selected from2-amino-6-chloropurineriboside-5′-triphosphate,2-aminopurine-riboside-5′-triphosphate;2-aminoadenosine-5′-triphosphate,2′-amino-2′-deoxycytidine-triphosphate, 2-thiocytidine-5′-triphosphate,2-thiouridine-5′-triphosphate, 2′-fluorothymidine-5′-triphosphate,2′-O-methyl inosine-5′-triphosphate 4-thiouridine-5′-triphosphate,5-aminoallylcytidine-5′-triphosphate,5-aminoallyluridine-5′-triphosphate, 5-bromocytidine-5′-triphosphate,5-bromouridine-5′-triphosphate, 5-bromo-2′-deoxycytidine-5′-triphosphate, 5-bromo-2′-deoxyuridine-5′-triphosphate,5-iodocytidine-5′-triphosphate, 5-iodo-2′-deoxycytidine-5′-triphosphate,5-iodouridine-5′-triphosphate, 5-iodo-2′-deoxyuridine-5′-triphosphate,5-methylcytidine-5′-triphosphate, 5-methyluridine-5′-triphosphate,5-propynyl-2′-deoxycytidine-5′-triphosphate,5-propynyl-2′-deoxyuridine-5′-triphosphate,6-azacytidine-5′-triphosphate, 6-azauridine-5′-triphosphate,6-chloropurineriboside-5′-triphosphate,7-deazaadenosine-5′-triphosphate, 7-deazaguanosine-5′-triphosphate,8-azaadenosine-5′-triphosphate, 8-azidoadenosine-5′-triphosphate,benzimidazole-riboside-5′-triphosphate,N1-methyladenosine-5′-triphosphate, N1-methylguanosine-5′-tri phosphate,N6-methyladenosine-5′-triphosphate, 06-methylguanosine-5′-triphosphate,pseudouridine-5′-triphosphate, or puromycin-5′-triphosphate,xanthosine-5′-triphosphate. Particular preference is given tonucleotides for base modifications selected from the group ofbase-modified nucleotides consisting of5-methylcytidine-5′-triphosphate, 7-deazaguanosine-5′-triphosphate,5-bromocytidine-5′-triphosphate, and pseudouridine-5′-triphosphate.

In some embodiments, modified nucleosides include pyridin-4-oneribonucleoside, 5-aza-uridine, 2-thio-5-aza-uridine, 2-thiouridine,4-thio-pseudouridine, 2-thio-pseudouridine, 5-hydroxyuridine,3-methyluridine, 5-carboxymethyl-uridine, 1-carboxymethyl-pseudouridine,5-propynyl-uridine, 1-propynyl-pseudouridine, 5-taurinomethyluridine,1-taurinomethyl-pseudouridine, 5-taurinomethyl-2-thio-uridine,1-taurinomethyl-4-thio-uridine, 5-methyl-uridine,1-methyl-pseudouridine, 4-thio-1-methyl-pseudouridine,2-thio-1-methyl-pseudouridine, 1-methyl-1-deaza-pseudouridine,2-thio-1-methyl-1-deaza-pseudouridine, dihydrouridine,dihydropseudouridine, 2-thio-dihydrouridine,2-thio-dihydropseudouridine, 2-methoxyuridine, 2-methoxy-4-thio-uridine,4-methoxy-pseudouridine, and 4-methoxy-2-thio-pseudouridine.

In some embodiments, modified nucleosides include 5-aza-cytidine,pseudoisocytidine, 3-methyl-cytidine, N4-acetylcytidine,5-formylcytidine, N4-methylcytidine, 5-hydroxymethylcytidine,1-methyl-pseudoisocytidine, pyrrolo-cytidine, pyrrolo-pseudoisocytidine,2-thio-cytidine, 2-thio-5-methyl-cytidine, 4-thio-pseudoisocytidine,4-thio-1-methyl-pseudoisocytidine,4-thio-1-methyl-1-deaza-pseudoisocytidine,1-methyl-1-deaza-pseudoisocytidine, zebularine, 5-aza-zebularine,5-methyl-zebularine, 5-aza-2-thio-zebularine, 2-thio-zebularine,2-methoxy-cytidine, 2-methoxy-5-methyl-cytidine,4-methoxy-pseudoisocytidine, and 4-methoxy-1-methyl-pseudoisocytidine.

In other embodiments, modified nucleosides include 2-aminopurine, 2,6-diaminopurine, 7-deaza-adenine, 7-deaza-8-aza-adenine,7-deaza-2-aminopurine, 7-deaza-8-aza-2-aminopurine,7-deaza-2,6-diaminopurine, 7-deaza-8-aza-2,6-diaminopurine,1-methyladenosine, N6-methyladenosine, N6-isopentenyladenosine,N6-(cis-hydroxyisopentenyl)adenosine,2-methylthio-N6-(cis-hydroxyisopentenyl) adenosine,N6-glycinylcarbamoyladenosine, N6-threonylcarbamoyladenosine,2-methylthio-N6-threonyl carbamoyladenosine, N6,N6-dimethyladenosine,7-methyladenine, 2-methylthio-adenine, and 2-methoxy-adenine.

In other embodiments, modified nucleosides include inosine,1-methyl-inosine, wyosine, wybutosine, 7-deaza-guanosine,7-deaza-8-aza-guanosine, 6-thio-guanosine, 6-thio-7-deaza-guanosine,6-thio-7-deaza-8-aza-guanosine, 7-methyl-guanosine,6-thio-7-methyl-guanosine, 7-methylinosine, 6-methoxy-guanosine,1-methylguanosine, N2-methylguanosine, N2,N2-dimethylguanosine,8-oxo-guanosine, 7-methyl-8-oxo-guanosine, 1-methyl-6-thio-guanosine,N2-methyl-6-thio-guanosine, and N2,N2-dimethyl-6-thio-guanosine.

In some embodiments, the nucleotide can be modified on the major grooveface and can include replacing hydrogen on C-5 of uracil with a methylgroup or a halo group.

In specific embodiments, a modified nucleoside is5′-O-(1-thiophosphate)-adenosine, 5′-O-(1-thiophosphate)-cytidine,5′-O-(1-thiophosphate)-guanosine, 5′-O-(1-thiophosphate)-uridine or5′-O-(1-thiophosphate)-pseudouridine.

In further specific embodiments, a modified RNA may comprise nucleosidemodifications selected from 6-aza-cytidine, 2-thio-cytidine,α-thio-cytidine, pseudo-iso-cytidine, 5-aminoallyl-uridine,5-iodo-uridine, N1-methyl-pseudouridine, 5,6-dihydrouridine,α-thio-uridine, 4-thio-uridine, 6-aza-uridine, 5-hydroxy-uridine,deoxy-thymidine, 5-methyl-uridine, pyrrolo-cytidine, inosine,α-thio-guanosine, 6-methyl-guanosine, 5-methyl-cytdine, 8-oxo-guanosine,7-deaza-guanosine, N1-methyl-adenosine, 2-amino-6-chloro-purine,N6-methyl-2-amino-purine, pseudo-iso-cytidine, 6-chloro-purine,N6-methyl-adenosine, α-thio-adenosine, 8-azido-adenosine,7-deaza-adenosine.

In the following, individual preferred aspects and embodiments of theinvention are described. Each of these aspects and embodiments, or anycombination thereof, may apply in the context of the present inventionas defined above and in the claims. In particular, any one of theindividual quality control steps, synthesis steps and/or purificationsteps described in the following, or any combination thereof, may applyto any embodiment of the inventive method.

Reverse Transcription of the Target RNA Sequence:

In order to generate a template DNA for RNA in vitro transcription, thetarget RNA sequence, which is preferably selected as described above, ispreferably reverse transcribed into a DNA sequence (cDNA, complementaryDNA). This cDNA may be produced e.g. by using a reverse transcriptaseand an RNA sequence comprising the target RNA sequence as template (thisis also termed herein as “enzymatic reverse transcription).Alternatively the reverse transcription may be performed in silico whichmeans that the reverse transcription is performed virtually e.g by acomputer.

Synthesis of a Template DNA Comprising a DNA Sequence Encoding the RNASequence:

For in vitro transcription, the template DNA preferably comprises atleast the following elements in 5′-3′ orientation:

a promoter/binding site for a DNA-dependent RNA polymerase such as T3,T7 and SP6 (e.g. as shown in FIG. 2); and

a DNA sequence encoding the target RNA sequence.

In case the encoded RNA sequence encodes a peptide or protein, theencoded RNA sequence, which is preferably selected as described above,may be optimized/engineered to generate proteins with desired features(optimized stability, defined localization, membrane integration etc.).

Optionally, the open reading frame encoding the protein encoded by theRNA is sequence-modified (exploiting the degeneration of the geneticcode) without altering the encoded protein sequence, for example byGC-enrichment (according to WO02098443), codon optimization (accordingto WO02098443), elimination of restriction sites used for sub-cloning,elimination of instability motifs (e.g. AU-rich elements, miRNA bindingsites). These AU-rich signatures are particularly prevalent in geneswith high turnover rates. Based on their sequence features andfunctional properties, AU-rich elements (AREs) can be categorized intothree classes (Chen et al, 1995): Class I AREs contain several dispersedcopies of an AUUUA motif within U-rich regions. C-Myc and MyoD containclass I AREs. Class II AREs possess two or more overlappingUUAUUUA(U/A)(U/A) nonamers. Molecules containing this type of AREsinclude GM-CSF and TNF-a. Class III ARES are less well defined. TheseU-rich regions do not contain an AUUUA motif.

Alternatively, the wild type nucleic acid sequence encoding a protein ofinterest may be selected.

The DNA sequence encoding the target RNA sequence (unmodified (wildtype) or modified) can be produced, for instance, by artificial genesynthesis e.g. by solid-phase DNA synthesis, by oligonucleotideannealing or by PCR.

Synthesis of the Template DNA by PCR:

The template DNA may be synthesized and/or amplified by PCR using thecDNA (complementary to the target RNA sequence) or any DNA comprisingthe cDNA (e.g. a plasmid vector comprising the cDNA) as template. Inthis case, the 5′-primer used for PCR preferably comprises the sequenceof a promoter of DNA-dependent RNA polymerase to generate a PCR productcomprising at least a promoter for a DNA-dependent RNA polymerase andthe DNA sequence encoding the target RNA sequence. This synthesized oramplified PCR product used as template for in vitro transcription istermed herein as template PCR product.

The quality of the template PCR product may be controlled bydetermination of the identity of the DNA sequence encoding the targetRNA sequence. Preferably, a method as described herein under section ‘A.Quality Control 1’ with respect to determination of the identity of theDNA sequence encoding the RNA sequence may be performed. Particularlypreferred is PCR or sequencing of the DNA sequence encoding the targetRNA sequence.

Synthesis of the Template DNA by Cloning of a DNA Sequence Encoding theRNA Sequence into a Plasmid DNA Vector and Subsequent Amplification:

One alternative for using a PCR product as template for in vitrotranscription is the use of plasmid DNA vectors comprising a DNAsequence encoding the RNA sequence (also termed herein “insert DNAsequence”) and a promoter of a DNA-dependent RNA polymerase. In thiscase plasmids can be chosen, which can be amplified e.g. in bacteriaparticularly E. coli by fermentation. This alternative has the advantagethat it produces less mutations in the amplified DNA compared to PCR.Alternatively, the insert DNA sequence may be amplified by PCR andtherefore the PCR product is used as template for in vitrotranscription.

Selection and Design of a Plasmid DNA Vector Backbone:

Plasmid DNA vectors for synthesis of the template DNA plasmids arepreferably selected depending on the host organism. Forproduction/replication/amplification of plasmid DNA, bacteria,particularly Escherichia coli (E. coli) is used.

Plasmids are frequently used as vectors in genetic engineering. Plasmidsserve as important tools in genetics and biotechnology labs, where theyare commonly used to multiply (make many copies of) or express(translate gene into proteins) particular genes. Many plasmids arecommercially available for such uses, including pDP (Ambion), pGEM(Promega), pBluescript (Stratagene), pCRII (Invitrogen), pUC57, pJ204(from DNA 2.0) and pJ344 (from DNA 2.0), pUC18, pBR322 and pUC19.

Commonly, cDNA encoding or corresponding to the RNA sequence of interest(target RNA sequence) is inserted into a plasmid that typically containsa number of features (possible features listed below). These include agene that makes the bacterial cells resistant to particular antibiotics(normally kanamycin or ampicillin), an origin of replication to allowbacterial cells to replicate the plasmid DNA, and a multiple cloningsite (MCS, or polylinker). A multiple cloning site is a short regioncontaining several commonly used restriction sites allowing the easyinsertion of DNA fragments at this location.

Although a very large number of host organisms and molecular cloningvectors are in use, the great majority of molecular cloning experimentsbegin with a laboratory strain of the bacterium Escherichia coli (E.coli) and a plasmid cloning vector. E. coli and plasmid vectors are incommon use because they are technically sophisticated, versatile, widelyavailable, and offer rapid growth of recombinant organisms with minimalequipment.

Particularly useful cloning vectors for E. coli are vectors based onpUC19 or pBR322 (J. Vieira, J. Gene. Band 19, Nummer 3, Oktober 1982, S.259-268, ISSN 0378-1119. PMID 6295879; Sue Lin-Chao et al. MolecularMicrobiology. 6, Nr. 22, November 1992, ISSN 0950-382X, S. 3385-3393,doi:10.1111/j.1365-2958.1992.tb02206.x, PMID 1283002, C.Helmer-Citterich et al. (1988). The EMBO journal 7(2), 557-66; C.Yanisch-Perron et al. (1985), Gene. Bd. 33, S. 103-119. PMID 2985470; F.Bolivar et al., Gene. 2, 95-113 (1977).; L. Covarrubias et al., Gene.13, 25-35 (1981)).

For the use as template in in vitro transcription reactions, the plasmidDNA vector typically carries a binding site for a DNA-dependent RNApolymerase, preferably for T3, T7 or SP6 polymerase (T3-, T7-, or SP6promoter).

To increase the transcription, translation and/or stability furtherelements can be included in the plasmid:

a 5′-UTR (particularly preferred are TOP-UTRs according to WO2013143700and WO2013143699);

a Kozak sequence, or another translation initiation element(CCR(A/G)CCAUGG (SEQ ID NO: 21)), where R is a purine (adenine orguanine) three bases upstream of the start codon (AUG), which isfollowed by another ‘G’. 5′UTR also have been known to form secondarystructures, which are involved in elongation factor binding);a 3′-UTR (particularly preferred are UTRs from stable RNAs particularlyfrom albumin gene, an α-globin gene, a β-globin gene, a tyrosinehydroxylase gene, a lipoxygenase gene, and a collagen alpha geneaccording to WO2013143700;a poly(A) sequence;a poly(C) sequence; and/ora stem-loop sequences, e.g. histone stem-loop sequences according toWO2012019780

Particularly preferred are plasmids based on the DNA plasmid pUC19. Thedifferent variants (pCV19, pCV26, pCV32, and pCV22 min) differ inrestriction sites and 5′- and/or 3′-UTRs. Vectors are preferably basedon pCV26 as shown in FIG. 3.

Synthesis of a Template Plasmid DNA Vector:

In certain embodiments, the template DNA comprising a nucleic acidsequence encoding an RNA may be a plasmid DNA vector.

Synthesis of a Template Plasmid DNA Vector by Cloning:

According to a preferred embodiment, a DNA plasmid vector backbone (asdefined above) is treated with a restriction endonuclease to linearizethe DNA at the site, where the DNA sequence encoding the target RNAsequence (the insert DNA sequence) will be inserted.

The restriction enzyme is commonly chosen so as to generate aconfiguration at the cleavage site on the vector that is compatible withthe one generated at the ends of the insert sequence. Typically, this isdone by cleaving the plasmid DNA vector backbone and insert DNA sequence(PCR product, DNA sequence synthesized by artificial gene synthesis e.g.by solid-phase DNA synthesis, or insert retrieved from a plasmid) withthe same restriction enzyme(s), for example EcoRI.

To facilitate an oriented integration, two different enzymes, generatingtwo different cleavage site-configurations may be chosen in order to addan insert into a vector (one enzyme at the 5′ end and a different enzymeat the 3′ end). This ensures that the insert will be integrated in thedesired orientation and prevents the vector from ligating to itselfduring the ligation process.

Recent vectors typically contain a variety of convenient cleavage sites,accumulated in the multiple cloning site (MCS) that are unique withinthe vector molecule (so that the vector can only be cleaved at a singlesite). Optionally the MCS is located within a reporter gene (frequentlybeta-galactosidase) whose inactivation can be used to distinguishrecombinant from non-recombinant constructs at a later step in theprocess (colonies without insert develop a blue color in the presence ofthe respective substrate and an (optionally) an inducer; blue whiteselection).

To improve the ratio of recombinant to non-recombinant constructs, thecleaved vector may additionally be treated with an enzyme (aphosphatase, e.g, alkaline phosphatase) that removes the 5′ phosphateand therefore prevents the ligase from being able to fuse the two endsof the linearized vector together, and therefore avoids self-ligation.Moreover, linearized vector molecules with dephosphorylated ends areunable to replicate, and replication can only be restored if insert DNAis integrated into the cleavage site.

DNA inserts, encoding the target RNA sequence, and the linearized vectorare preferably mixed together at appropriate concentrations (commonly1:1 or 1:3 molar ratio) and exposed to an enzyme (DNA ligase) thatcovalently links compatible ends together (that is: sticky ends producedby the same or compatible restriction endonucleases, or blunt ends).This joining reaction is commonly termed ligation (e.g., T4 DNA Ligase).The resulting DNA mixture is then ready for introduction into the hostorganism (Escherichia coli) by means of common transformationtechniques, including chemical transformation or electroporation.

Synthesis of the Template Plasmid DNA Vector by OligonucleotideAnnealing:

Alternatively, the template DNA plasmid vector may be synthesized byintegrating the DNA sequence encoding the target RNA sequence byoligonucleotide annealing. In this case, the insert DNA sequence isdirectly synthesized into the sequence of a plasmid DNA vector backbone.This alternative is particularly preferred if the target RNA sequence isnot a wild type sequence comprised in a naturally occurring RNA andtherefore the reverse transcription cannot be performed by an enzymaticreverse transcription.

The quality of the template plasmid DNA may be controlled bydetermination of the identity of the DNA sequence encoding the targetRNA sequence. Preferably, a method as described herein under section ‘A.Quality Control 1’ with respect to determination of the identity of theDNA sequence encoding the RNA sequence may be performed. Particularlypreferred is restriction analysis and sequencing of the insert DNAsequence.

Amplification of the Template Plasmid DNA Vector:

Transformation:

The template DNA plasmid vector may be amplified by propagation inbacteria, particularly in E. coli. Therefore the plasmid is insertedinto bacteria by a process called transformation. Particularly preferredare Escherichia coli host strains.

Different methods for transformation of plasmid DNA are well known for aperson skilled in the art, comprising electroporation ofelectro-competent cells or heat shock transformation of chemicallycompetent cells.

Particularly preferred is the transformation of chemical competent cellsby heat shock, using strains comprising DH5alpha, DH10B, Mach1, OmniMax2, Stbl2, Top 10, Top 10F.

In this context, 1-10 ng, preferably (4-5 ng) purified plasmid are mixedwith 50 μl chemical competent cells, e.g. CaCl₂-competent cells,preferably DH5 alpha. The mixture is incubated for at least 30 minutesat 0-5° C. Subsequently, the mixture is incubated for 20 s at 42° C.After the heat shock the mixture is incubated at 0-5° C. for severalminutes.

For plating the cells, 900 μl LB-medium is added; incubated for 1-3 h at37° C. and plated on LB agar plates containing antibiotics e.g.ampicillin or kanamycin, dependent on the antibiotic resistance geneencoded on the vector, and incubated 12-24 h at 37° C.

The transformation efficacy is evaluated based on the number of coloniesformed. E. coli cells are transformed for each production campaign. Onlybacteria that take up copies of the plasmid survive, since the plasmidmakes them resistant (ampicillin resistance). In particular, theresistance genes are expressed (used to make a protein) and theexpressed protein either breaks down the antibiotics or prevents it frominhibiting certain bacterial pathways. In this way, the antibiotics actas a filter to select only the bacteria containing the plasmid DNA. Nowthese bacteria can be grown in large amounts, harvested, and lysed toisolate the plasmid of interest.

Fermentation:

In a preferred embodiment, a single transformed E. coli colony is takenfrom the agar plate and used to inoculate a liquid LB medium culture(containing antibiotics, e.g. 100 μg/ml ampicillin). The culture isgrown for 4-8 h at 37° C. under shaking. 5-10 ml of that culture arethen used to inoculate a larger volume (e.g. 1 l LB medium containingantibiotic) contained in the fermenter.

During fermentation overnight (12-20 h), standard parameters areprecisely regulated and continuously monitored (e.g., pH, oxygenconcentration, anti-foam, shaking, temperature). The cell density iscontrolled by photometric determination at 600 nm. After fermentation, aculture sample is preferably taken for quality control and cells areharvested and centrifuged. The cell pellet can be stored at ≤−20° C.

Quality Control: Isolation of Plasmid DNA and Subsequent Analysis of thePlasmid DNA

Plasmid DNA is preferably isolated from 1 ml of E. coli cells using astandard plasmid preparation kit known in the art. The concentration ofthe isolated plasmid DNA is determined by a standard photometric methodfor nucleic acids via measurement of the absorption at 260 nm (OD260) toestimate the expected total plasmid DNA yield of the whole fermentation.To confirm the correct gene, the restriction pattern of the extractedplasmid DNA is preferably analyzed and evaluated according to ‘QualityControl 1’ as described herein.

Alternatively, a person skilled in the art may conduct a PCR usingsuitable primer pairs with E. coli cells as template. The PCR productmay be analyzed using agarose gel electrophorese (see section ‘A.Quality Control 1’)

Isolation of Plasmid DNA by Mini Preparation Kit:

Preparations of plasmid DNA can be obtained by various methods known inthe art, comprising the alkaline lysis method and the boiling method(see e.g. Sambrook et al., Molecular Cloning, a laboratory manual, 2ndedition, Cold Spring Harbor Laboratory Press 1989. 1.25)

Moreover, various kits for preparation of plasmid DNA are commerciallyavailable (e.g. NucleoSpin Plasmid Kit; Macherey Nagel; QIAprep Miniprepkit; QIAGEN) which commonly use a silica membrane that binds DNA in thepresence of a high concentration of chaotropic salt, and allows elutionin a small volume of low-salt buffer. This technology eliminates timeconsuming phenol-chloroform extraction and alcohol precipitation.

The concentration of the isolated plasmid DNA is determined preferablyby a standard photometric method for nucleic acids via measurement ofthe absorption at 260 nm (OD260).

Quality Control of the Plasmid DNA:

Determination of the identity of the DNA sequence encoding the targetRNA sequence. Preferably, any method known in the art or as described insection ‘A. Quality Control 1’ herein to determine the identity of theDNA sequence encoding the target RNA sequence may be performed.Particularly preferred is restriction analysis.

Plasmid Preparation:

Plasmid DNA is isolated from the frozen E. coli cell culture pellet byany method known in the art, preferably by chromatography using a gigapreparation kit, most preferably by an endotoxin-free giga preparationkit (e.g. EndoFree Plasmid Giga Kit of Qiagen, or Endotoxin-free plasmidDNA purification of Macherey Nagel). For the production of medicamentsit is very important to minimize the endotoxin level during theproduction process.

The concentration of the isolated plasmid DNA is preferably determinedby a standard photometric method for nucleic acids via measurement ofthe absorption at 260 nm (OD260).

The yield of the isolated plasmid DNA is calculated. (Determination ofthe content of the template DNA plasmid)

Quality Control of the Plasmid DNA: Determination of the Identity of theDNA Sequence Encoding the Target RNA Sequence and Determination ofPurity of Template DNA Plasmid

Any method as described in section ‘A. Quality Control 1’ herein todetermine the identity of the DNA sequence encoding the target RNAsequence may be performed. Particularly preferred is restrictionanalysis and sequencing of the insert DNA sequence. In addition, thepurity of the plasmid preparation is preferably determined. Any methodas described in section ‘A. Quality Control 1’ to determine the puritymay be used. Particularly preferred is the determination of RNAcontaminations, determination of endotoxins, determination of proteincontent, determination of bioburden, and determination of residual E.coli DNA.

Linearization:

The isolated plasmid DNA is typically linearized by a specific,preferably singular, enzymatic restriction to provide a defined lineartemplate for the following RNA in vitro transcription process. Thisensures a defined termination of the in vitro RNA transcriptionprocedure by avoiding transcriptional read-through. The linearized DNAtemplate is preferably purified and the content and yield of the linearDNA is determined.

Preferred endonucleases for linearizing the pDNA template include BciVI,XbaI, SpeI, HindIII, NotI, EcoRI, NdeI, AflII, HindIII, and SapI. Themost preferred restriction enzyme is EcoRI.

Further details regarding restriction digestion is disclosed in section‘A. Quality Control 1’ herein.

Particularly preferred are the following conditions:

Composition of One Reaction:

1 μg plasmid DNA

0.5 μl reaction buffer

3 units restriction enzyme

Add. 5 μl with WFI (water for injection)

The composition is calculated according to the amount of plasmid DNAused for linearization (at least 1000 reactions, preferably 10000reactions).

The reaction is incubated for 4 to 5 hours at 37° C.

Purification of the Linearized Template Plasmid DNA:

The linearized template DNA is preferably purified. Different methodscan be used, e.g. phenol/chloroform extraction with subsequent alcoholprecipitation, chromatographic methods or filtration methods, orsilica-based DNA capture methods.

This step also ensures the reduction of impurities (e.g. proteins) fromthe previous manufacturing steps, including E. coli proteins,restriction enzymes and BSA (contained in reaction buffers).

In this context, phenol/chloroform/isoamylalcohol precipitation withsubsequent isopropanol precipitation is particularly preferred. Thesemethods are described in Sambrook et al., Molecular Cloning, SecondEdition, 1989, Cold Spring Harbor Laboratory Press).

After precipitation, the plasmid DNA is resuspended in a suitablebuffer, preferably water for injection.

Quality Control of Linearized Template Plasmid DNA Vector: Determinationof Completeness of Linearization, Estimation of RNA Yield andDetermination of Identity of RNA

Determination of Completeness of Linearization

Linear template plasmid DNA is preferably analyzed forsuccessful/complete linearization. The band uniqueness and band size ofthe linear plasmid DNA are preferably analyzed via agarose gelelectrophoresis. The agarose gel electrophoresis is carried out asdescribed in section ‘Quality Control 1’ herein in the context ofrestriction analysis. Alternatively, any other method known in the artfor determining DNA fragments may be used, in particular the methods asdescribed herein. Preferably, 0.5 μg linearized plasmid DNA are analyzedby agarose gel electrophoresis.

Therefore, in one aspect the present invention provides a method foranalysis of successful linearization of plasmid DNA, in particular, amethod for analysis of successful linearization of plasmid DNA for useas quality control in the manufacture of plasmid DNA and/or in a methodfor producing RNA.

Test Transcription:

A small scale transcription test with linear template DNA into RNA via apolymerization reaction by RNA polymerase is preferably performed. Thissmall scale test in vitro transcription is performed to estimate theexpected yield of in vitro transcribed RNA and to analyze the identityof the in vitro transcribed RNA.

An in vitro transcription reaction commonly contains, but is not limitedto, DNA template, a suitable buffer (HEPES, Tris-HCl pH 7.5), DNAdependent RNA polymerase (e.g. T7, T3, SP6), a suitable nucleotidemixture (natural and/or modified nucleotides), DTT, spermidine, NaCl,MgCl₂, RNAse inhibitor and pyrophosphatase. More details are describedin the section RNA transcription herein specifically dedicated to invitro transcription as such.

Subsequently, the in vitro transcribed RNA is preferably purified.Different methods for RNA purification are known in the art includingphenol/chloroform/isoamylalcohol extraction with subsequent ethanol orisopropanol precipitation, precipitation with alcohol and a monovalentcation such as sodium or ammonium ion, LiCl precipitation,chromatographic methods or filtration methods.

In this context, LiCl precipitation is particularly preferred. LiClprecipitation is preferably performed by adding 50% of the volume 8 MLiCl. The reaction is mixed and incubated at room temperature.Subsequently the reaction is centrifuged, the supernatant discarded andthe RNA pellet washed with 75% ethanol. After drying the RNA ispreferably resuspended in water.

Estimation of RNA Yield by Photometric Determination of the RNAConcentration

The concentration of the test in vitro transcription is preferablydetermined by photometry as described in section ‘B. Quality Control 2’.Therefore, the yield of in vitro transcribed RNA can be estimated.

Determination of RNA Identity in Test In Vitro Transcription

The RNA identity in the test in vitro transcription is preferablydetermined by any method known in the art, particularly by any methoddescribed herein in section ‘B. Quality Control 2’. Particularlypreferred is agarose gel electrophoresis as described herein in section‘B. Quality Control 2’.

Therefore, in one aspect the present invention provides a small scaletest in vitro transcription used as quality control for the manufactureof template DNA and/or for the manufacture of in vitro transcribed RNA.It is used for estimation of the yield of in vitro transcribed RNA andto analyze for identity of the in vitro transcribed RNA.

A. Quality Control 1

In this section (section A and subsections), preferred steps aredescribed for controlling the quality of the template DNA comprising anucleic acid sequence encoding the RNA. In particular, this sectionrelates to preferred steps for determination of the template DNAcontent, determination of the identity of the DNA sequence encoding thetarget RNA sequence and/or determination of the purity of the templateDNA.

A.1 Determination of Template Plasmid DNA Content

The concentration of the isolated template plasmid DNA (dsDNA) ispreferably determined by a standard photometric method for nucleic acidsvia measurement of the absorption. Moreover, the OD 260/280 value ispreferably determined which measures the purity of a nucleic acidsample. For pure DNA, A260/280 is approximately 1.8.

A.2 Determination of the Identity of the DNA Sequence Encoding theTarget RNA Sequence

A.2.1 Determination of the Identity of the DNA Sequence Encoding theTarget RNA Sequence by PCR:

To confirm that the obtained template DNA comprises the nucleic acidsequence encoding the RNA sequence, PCR with appropriate primers may beperformed. Primers located in the nucleic acid sequence encoding thetarget RNA sequence or primers located outside of the nucleic acidsequence encoding the target RNA sequence may be used for PCR.

If a plasmid DNA vector is used as template for the in vitrotranscription, also primers located on the backbone of the plasmid DNAvector may be used, e.g. standard primers such as M13, Sp6, or T7primers flanking the insert DNA sequence encoding the target RNAsequence.

The resulting PCR-amplified products may be analyzed by any method knownin the art such as by gel electrophoresis e.g. agarose gelelectrophoresis, DNA sequencing or chromatography e.g. HPLC).Particularly preferred is the analysis by agarose gel electrophoresis orHPLC.

In one aspect, the present invention provides PCR used as a method foranalysis of template DNA, for controlling the identity of the DNAsequence encoding the target RNA sequence. Particularly, this method isused as a quality control for the production of template DNA in a methodfor producing RNA, preferably in the production process of in vitrotranscribed RNA.

A.2.2 Determination of the Identity of the DNA Sequence Encoding theTarget RNA Sequence by Restriction Analysis

Alternatively or additionally to other methods, such as PCR, restrictionanalysis of the template plasmid DNA vector comprising the insert DNAsequence encoding the target RNA sequence is preferably conducted andthe resulting fragments of the plasmid DNA vector are analyzed toconfirm that the template plasmid DNA vector contains the insert DNAsequence encoding the target RNA sequence.

Restriction Reaction:

Restriction enzymes specifically bind to and cleave double-stranded DNAat specific sites within or adjacent to a particular sequence known asthe recognition site. Most of the restriction enzymes recognize aspecific sequence of nucleotides that are four, five or six nucleotidesin length and display twofold symmetry. Some cleave both strands exactlyat the axis of symmetry, generating fragments of DNA that carry bluntends; others cleave each strand at similar locations on opposite sidesof the axis of symmetry, creating fragments of DNA that carrysingle-stranded termini (See Definitions).

The reaction conditions used for the restriction digestion are dependenton the used restriction enzymes. Particularly, the salt concentrationdiffers depending on the used restriction enzyme. Therefore, themanufacturer of restriction enzymes optimized buffers for theirrestriction enzymes.

Preferred conditions for a restriction reaction with one restrictionenzyme are:

0.5 μg plasmid DNA (0.2-2 μg plasmid DNA)

1.5 μl 10× reaction buffer

1 μl restriction enzyme (1 μl normally comprises 1 u)

Add. 15 μl WFI (water for injection)

Preferred conditions for a restriction reaction with two restrictionenzymes are:

0.5 μg plasmid DNA (0.2-2 μg plasmid DNA)

1.5 μl 10× reaction buffer

1 μl restriction enzyme 1 (1 μl normally comprises 1 u)

1 μl restriction enzyme 2 (1 μl normally comprises 1 u)

Add. 15 μl WFI (water for injection)

The restriction reaction is typically mixed as shown above and incubatedpreferably for 1-4 hours at 37° C.

In this context, it is particularly preferred that restriction enzymesare combined, which cut 5′- and 3′ of the insert DNA sequence.Alternatively, a specific combination of restriction enzymes is chosendependent on the insert DNA sequence. In this case, it is particularlypreferred to choose a restriction enzyme, which cuts only once in theDNA plasmid backbone and a restriction enzyme, which cuts once in theinsert DNA sequence.

It is particularly preferred to perform at least one, 2, 3, 4 or 5different restriction reactions using different restriction enzyme(s)(combinations) in order to control the identity of the insert DNAsequence comprising the nucleic acid sequence encoding the target RNAsequence.

The identity of the insert DNA sequence contained in the templateplasmid DNA vector is controlled by enzymatic restriction and subsequentanalysed preferably via agarose gel electrophoresis. For this purpose,template plasmid DNA is incubated with a certain number of specificrestriction enzymes (preferably in at least five independent reactions)leading to a specific fragmentation of the template plasmid DNA vector.Subsequently, the restricted DNA samples are analyzed by separation ofthe obtained fragments of different sizes e.g. on an agarose gel or bye.g. by HPLC. The received fragmentation pattern of the DNA is comparedto the theoretically expected restriction pattern.

Analysis of the DNA Fragments Resulting from Restriction Reaction:

Exemplary methods for analyzing DNA fragments are, for instance, agarosegel electrophoresis, polyacrylamide gel electrophoresis, chip gelelectrophoresis, capillary electrophoresis, fluorescence-based automaticDNA-fragment analysis and HPLC (e.g. WAVE™ DNA Fragment AnalysisSystem).

Particularly preferred is agarose gel electrophoresis as described inSambrook et al., Molecular Cloning, a laboratory manual, 2nd edition,Cold Spring Harbor Laboratory Press 1989. 6.

Electrophoresis through agarose gels is a method to separate DNAfragments. The DNA can be determined in the agarose gel by addition ofthe fluorescent intercalating dye ethidium bromide or other commerciallyavailable DNA dyes (SybrSafe DNA stain, Cybr Green, Orange DNA loadingdye)

Different running buffers can be used, e.g. TBE (Tris-borate) or TAE(Tris-acetate) buffer:

1×TBE (Tris-borate):

89 mM Tris base

89 mM boric acid

2 mM EDTA

1×TAE (Tris-acetate):

40 mM Tris

20 mM acetic acid

1 mM EDTA

For the preparation of the agarose gel 0.3-5% (w/v) agarose or morepreferably 0.8% (w/v) agarose is melted in 1× running buffer, preferably1×TBE buffer. Ethidium bromide is added to the solution, preferably 1-5μl per 100 μl agarose gel solution.

The solution is poured into a mold and allowed to harden. When anelectric field is applied across the gel, DNA, which is negativelycharged, migrates to the anode. As running buffer the same buffer asused for preparation of the agarose gel is used.

Loading buffer (e.g. 6× Orange DNA Loading Dye) is added to the sampleand loaded onto the agarose gel. In this context the whole reaction (15μl) is mixed with an appropriate volume of loading buffer e.g. 3 μl 6Orange DNA Loading Dye.

After gel running the DNA fragments can be determined by ultravioletlight. The pattern of fragments can be compared to the predictedrestriction pattern and therefore allows the determination if thecorrect DNA sequence encoding the target RNA sequence is integrated intothe plasmid.

Therefore, in one aspect, the present invention provides restrictionanalysis used as a method for analysis of plasmid DNA, particularly forcontrolling the identity of the insert DNA sequence. Particularly thismethod is used as a quality control for the production of templateplasmid DNA in a method for producing RNA, preferably in a productionprocess of in vitro transcribed RNA.

A.2.3 Determination of the Identity of the DNA Sequence Encoding theTarget RNA Sequence by DNA Sequencing:

Automated DNA sequencing of the insert DNA sequence of the plasmid DNAor of the PCR product encoding the target RNA sequence may be performedto confirm the identity of the DNA sequence encoding the target RNAsequence. The DNA sequencing may be performed by any method known in theart, particularly by any method defined herein. Selection of appropriateprimers for DNA sequencing ensures that the complete length of the DNAsequence encoding the target RNA sequence is completely covered for bothcomplementary strands of the DNA primers (primers flanking the DNAsequence encoding the target RNA sequence e.g. the insert DNA sequence,located on the backbone of the plasmid, e.g., M13 forward, and M13reverse). The received sequence information is compared to the expectedsequence of the DNA sequence encoding the target RNA sequence.

Therefore, it is particularly preferred in the context of the presentinvention to confirm or to control the identity of the DNA sequenceencoding the target RNA sequence. In this context it is particularlypreferred to use primers which lay 5′ and/or 3′ of the DNA sequenceencoding the target RNA sequence e. g. comprised in the template plasmidDNA vector or in the template PCR product.

The following primer is particularly preferred:

(SEQ ID NO: 7) M13-universal Primer: 5′-CGCCAGGGTTTTCCCAGTCACGAC

Therefore, in one aspect the present invention provides DNA sequencingused as a method for analysis of template DNA, particularly forcontrolling the identity of the DNA sequence encoding the target RNAsequence. Particularly this method is used as a quality control for theproduction of template DNA in a method for producing RNA, preferably ina production process of in vitro transcribed RNA.

A.3 Determination of Purity of Template Plasmid DNA Preparation:

A.3.1 Determination of RNA Contaminations in the Template DNAPreparation Using RNAse Treatment

Template DNA may further be controlled with respect toRNA-contamination. Preferably, the template DNA e.g. plasmid DNA isincubated with RNase A. Afterwards the concentration of the purifiedtemplate DNA is determined again and the difference before and afterRNase treatment is calculated.

The following reaction is particularly preferred:

1-20 μg template DNA, preferably 10-15 μg template DNA are incubatedwith 1 μl RNAse A (1 g/l) for 1 h at 37° C.

Nucleotides are separated e.g. by alcohol precipitation, chromatography,preferably on Sephadex columns.

Preferably, the concentration of the isolated template DNA, preferablyafter RNase A digestion, is determined by a standard photometric methodfor nucleic acids via measurement of the absorption at 260 nm (OD260)(see above).

Calculation of the percentage of template DNA contained in the templateDNA preparation:

${\%\mspace{14mu}{template}\mspace{14mu}{DNA}} = {\frac{{concentration}\mspace{14mu}{of}\mspace{14mu}{nucleic}\mspace{14mu}{acids}\mspace{14mu}{after}\mspace{14mu}{RNase}\mspace{14mu} A\mspace{14mu}{digestion}}{{concentration}\mspace{14mu}{of}\mspace{14mu}{nucleic}\mspace{14mu}{acids}\mspace{14mu}{before}\mspace{14mu}{RNase}\mspace{14mu} A\mspace{14mu}{digestion}} \times 100\%}$

Therefore, in one aspect the present invention provides RNAse digestionused as a method for analysis of DNA, particularly for controlling thecontamination with RNA. Particularly this method is used as a qualitycontrol for the production of template DNA in a method for producingRNA, preferably in a production process of in vitro transcribed RNA.

A.3.2 Determination of Endotoxins in Template DNA Preparation:

A test for bacterial endotoxins is preferably carried out in order todetermine the presence and/or the amount of endotoxins in the templateDNA preparation. Preferably, endotoxins of gram-negative bacterialorigin are detected and/or quantified by using amoebocyte lysate fromhorseshoe crab (Limulus polyphemus or Tachypleus tridentatus). Theprinciple has been discovered by Levin (Levin, J. 1979. The reactionbetween bacterial endotoxin and amebocyte lysate, p. 131-146. In E.Cohen (ed.), Biomedical Applications of the Horseshoe Crab (Limulidae),Progress in Clinical and Biological Research, Vol. 29. Alan R. Liss,Inc., New York).

In general, there are at least 3 techniques for performing this test:the gel-clot technique, which is based on gel formation; theturbidimetric technique, based on the development of turbidity aftercleavage of an endogenous substrate; and the chromogenic technique,based on the development of colour after cleavage of a syntheticpeptide-chromogen complex.

Preferred is the LAL-test. The amount of endotoxins per volume ofplasmid DNA is determined and evaluated via kinetic-turbidometric LAL(Limulus-Amoebocyte-Lysate) test according to Ph. Eur. 2.6.14(Pharmacopoea Europaea).

Therefore, in one aspect the present invention provides a method fordetermination of endotoxins in DNA preparations, preferably plasmid DNApreparations, particularly used as quality control for the production ofplasmid DNA. Particularly, this method is used as a quality control forthe production of template plasmid DNA in a method for producing RNA,preferably in a production process of in vitro transcribed RNA.

A.3.3 Determination of Protein Concentration in Template DNAPreparation:

The total protein content per volume of template plasmid DNA ispreferably calculated. Several different methods are known in the artfor detection of protein, including UV absorbance measurements at 280 nm(due to the presence of aromatic amino acids), the Lowry assay, theBiuret assay, the Bradford assay, and the BCA (Bichinonic Acid) assay.

The BCA (Bichinonic Acid) assay, a colorimetric method of detection isbased on complexation of proteins with copper and BCA. The total proteinconcentration contained in the RNA is measured via absorption at 562 nmcompared to a protein standard (BSA). The principle of the bicinchoninicacid (BCA) assay is similar to the Lowry procedure (Lowry, O. H. et al,J. Biol. Chem., 193, 265-275 (1951)). Both rely on the formation of aCu²⁺-protein complex under alkaline conditions, followed by reduction ofthe Cu²⁺ to Cu⁺. The amount of reduction is proportional to the proteinpresent. It has been shown that cysteine, cystine, tryptophan, tyrosine,and the peptide bond are able to reduce Cu²⁺ to Cu⁺. BCA forms apurple-blue complex with Cu⁺ in alkaline environments, thus providing abasis to monitor the reduction of alkaline Cu²⁺ by proteins atabsorbance maximum 562 nm.

Another method, which can be used for the determination of protein isthe Bradford method. The Bradford assay, a colorimetric protein assay,is based on an absorbance shift of the dye Coomassie Brilliant BlueG-250 in which under acidic conditions the red form of the dye isconverted into its bluer form to bind to the protein being assayed. The(bound) form of the dye has an absorption spectrum maximum historicallyheld to be at 595 nm. The cationic (unbound) forms are green or red. Thebinding of the dye to the protein stabilizes the blue anionic form. Theincrease of absorbance at 595 nm is proportional to the amount of bounddye, and thus to the amount (concentration) of protein present in thesample.

Particularly preferred is the BCA assay. For performing a BCA assay,several commercially available kits may be used.

Therefore, in one aspect the present invention provides a method fordetermination of protein in DNA preparations, preferably plasmid DNApreparations, particularly used as quality control in the manufacture ofplasmid DNA and/or in a method for producing RNA, such as themanufacture of in vitro transcribed RNA.

A.3.4 Determination of the Bioburden in Template DNA Preparation:

To determine sterility of the template DNA preparation, a PCR usinguniversal bacterial primers (detecting universal occurring genes inbacteria) may be performed. Moreover, a plating assay may be conducted.

Particularly preferred is a plating assay according to PhEur 2.6.12.:

For determination of the bioburden the presence/absence of bacteria istested under aerobe and anaerobe conditions after plating the plasmidDNA on agar- and/or glucose plates and incubation for several days (e.g.5 and 7 days, respectively). The bioburden is assessed by counting thebacteria clones grown on bacteria plates.

For this purpose, different media for plating can be used. Tryptic SoyAgar (TSA) (Soybean Casein Digest Agar (CSA)) and Sabouraud Glucose (2%)Agar plates are particularly preferred.

Therefore, in one aspect the present invention provides a method fordetermination of the bioburden in DNA preparations, preferably plasmidDNA preparations, particularly used as quality control for themanufacture of plasmid DNA and/or for the manufacture of in vitrotranscribed RNA.

A.3.5 Determination of Residual Bacterial DNA:

In case E. coli is used for amplification of the template plasmid DNA,the residual E. coli DNA is preferably determined.

Residual E coli DNA may be detected via PCR, preferably via quantitativePCR (qPCR) using primers and probes specific for E. coli genes. In thiscontext primers and probes specific for any genomic sequence or genecomprised in the respective bacterial strain (e.g. E. coli strain) isparticularly useful to perform a PCR or qPCR to determine residualbacterial DNA. Particularly preferred are primers and probes specificfor the E. coli gene uidA.

Plasmid DNA is checked for residual E. coli DNA. For this purposequantitative PCR (qPCR) is performed with the plasmid DNA sampletogether with a positive and a negative control and the calculatednumber of copies of genomic E. coli DNA is assessed. For this purposethe E. coli specific gene uidA is amplified and quantified. Preferablythe Light Cycler from Roche is used in combination with FastStart DNAMasterPlus Hybridization Probes.

The following primers and probes are preferably used for thequantitative PCR detecting the uidA gene:

(SEQ ID NO: 8) Primer EC 679U: GGACAAGGCACTAGCG  (SEQ ID NO: 9)Primer EC 973 L: ATGCGAGGTACGGTAGGA  (SEQ ID NO: 10)Probe EC1 FL: CATCCGGTCAGTGGCAGT-FL  (SEQ ID NO: 11)Probe EC1 LC : LC640-AAGGGCGAACAGTTCCTGA-ph 

Alternatively, any other gene of the respective bacterial strain(particularly E. coli strain) used for fermentation may be used for thePCR or quantitative PCR.

Therefore, in one aspect the present invention provides a method fordetermination of residual bacterial DNA particularly used as qualitycontrol in the manufacture of plasmid DNA and/or in a method forproducing RNA, such as the manufacture of in vitro transcribed RNA.

A.3.6 Determination of RNase Contaminations in Template DNA:

The template DNA (e.g. the linear template plasmid DNA) is preferablyanalyzed for RNase contamination using commercially available RNasedetection kits, including RNaseAlert® (Applied Biosystems), RNasecontamination assay (New England Biolabs) or an assay where theincubation of the template DNA with a reference RNA serves as a readoutfor RNase contamination.

The template DNA may be analyzed for RNase contamination by using theRNaseAlert® kit, which utilizes an RNA substrate tagged with afluorescent reporter molecule (fluor) on one end and a quencher of thatreporter on the other. In the absence of RNases, the physical proximityof the quencher dampens fluorescence from the fluor. In the presence ofRNases, the RNA substrate is cleaved, and the fluor and quencher arespatially separated in solution. This causes the fluor to emit a brightgreen signal when excited by light of the appropriate wavelength.Fluorescence can be readily detected with a filter-based ormonochromator-based fluorometer.

The template DNA may be alternatively analyzed for RNase contaminationby using an RNase Contamination Assay Kit (New England Biolabs) whichdetects general RNase activities including non-enzyme based RNAdegradation due to heavy metal contamination in samples and high pH. Theassay probe is a fluorescein labeled RNA transcript (300-mer). Afterincubation with a pDNA sample the integrity of the RNA probe is analyzedon denaturing PAGE followed by SYBR Gold staining or preferably byscanning with a FAM/Fluorescein capable imaging system.

In a preferred embodiment, the template DNA is analyzed for RNasecontamination by incubation of the template DNA (preferably the lineartemplate plasmid DNA) with a reference RNA and subsequent analysis viaRNA agarose gel electrophoresis. In case of absence of RNase both thelinear DNA and the reference RNA can be detected on the agarose gel, incase of RNase contamination, only the DNA band can be detected.

Therefore in one aspect the present invention provides a method fordetermination of RNases particularly used as quality control for themanufacture of template DNA and/or for the manufacture of in vitrotranscribed RNA.

RNA Transcription

RNA can be produced “in vitro”, for example, from a PCR-based DNAtemplate, or a plasmid DNA based linearized DNA template using DNAdependent RNA polymerases.

Particularly preferred is in vitro transcription of RNA using alinearized plasmid DNA template.

The linearized template DNA plasmid produced in the previous steps istranscribed using DNA dependent RNA in vitro transcription. Thatreaction typically comprises a transcription buffer, nucleotidetriphosphates (NTPs), an RNase inhibitor and a DNA-dependent RNApolymerase. The NTPs can be selected from, but are not limited to, thosedescribed herein including naturally occurring and modified NTPs. TheDNA-dependent RNA polymerase can be selected from, but is not limitedto, T7 RNA polymerase, T3 RNA polymerase, SP6 RNA polymerase and mutantpolymerases such as, but not limited to, polymerases able to incorporatemodified nucleic acids.

Particularly preferred is T7 RNA polymerase as an enzyme for RNA invitro transcription.

During polymerization, the mRNA may be co-transcriptionally capped atthe 5′ end with a standard cap analogue as defined herein (e.g.N7-MeGpppG).

As transcription buffer following buffers are preferred: 40 mM Tris pH7.5 or 80 mM HEPES.

80 mM HEPES is particularly preferred.

Template DNA: 10-500 μg/ml, particularly preferred are 50 μg/ml

Nucleotide triphosphates of the desired chemistry are used, includingnaturally occurring nucleotides (e.g. at least one of the nucleotidesATP, CTP, UTP and GTP) and/or modified nucleotides, preferably modifiednucleotides as described herein, or any combination thereof.

ATP, CTP, UTP and GTP are preferably used in a concentration of 0.5-10mM, preferably in a concentration of 3-5 mM and most preferably in aconcentration of 4 mM.

Useful guanine analogs include, but are not limited to, N7-MeGpppG(=m7G(5′)ppp(5′)G), m7G(5′)ppp(5′)A, ARCA (anti-reverse CAP analogue,modified ARCA (e.g. phosphothioate modified ARCA), inosine,N1-methyl-guanosine, 2′-fluoro-guanosine, 7-deaza-guanosine,8-oxo-guanosine, 2-amino-guanosine, LNA-guanosine, and2-azido-guanosine. If 5′-CAP (cap analog) is used, the concentration ofGTP is decreased compared to the other used nucleotides. Preferably 10to 50% of GTP is used compared to the concentration of ATP, CTP and UTP.Most preferably 20-30% of GTP is used.

Furthermore the cap analog is used in a concentration which is at leastthe same as the concentration of ATP, CTP and UTP.

The ratio of cap analog:GTP can be varied from 10:1 to 1:1 to balancethe percentage of capped products with the efficiency of thetranscription reaction, preferably a ratio of cap analog:GTP of 4:1-5:1is used. In this context it is particularly preferred to use 5.8 mM Capanalog and 1.45 mM GTP if ATP, UTP and CTP are used in a concentrationof 4 mM.

MgCl₂ can optionally be added to transcription reaction. Preferred is aconcentration of 1-100 mM. Particularly preferred is a concentration of5-30 mM and most preferably 24 mM MgCl₂ is used.

Spermidine can optionally be added to the transcription reaction,preferably 1-10 mM, most preferably 2 mM spermidine.

Dithiothreitol (DTT) can optionally be added to the transcriptionreaction, preferably at a concentration of 1-100 mM, more preferably10-100 mM, most preferably 40 mM.

An RNase inhibitor can optionally be added to the transcriptionreaction, preferably 0.1-1 U/μl, most preferably 0.2 U/μl.

E. coli pyrophosphatase can optionally be added to the transcriptionreaction, preferably in a concentration of 1-10 U/μg template DNA, andmost preferably in a concentration of 5 U/μg template DNA. This ensuresthat magnesium, which is essential for transcription, remains insolution and does not precipitate as magnesium pyrophosphate.

The following viral DNA-dependent RNA polymerases can be used: T3, T7and Sp6 polymerases. 1-1000 Units/μg DNA can be used. Preferably in aconcentration of 100 U/μg DNA.

BSA can optionally be used, preferably in a concentration of 1-1000μg/ml, most preferably in a concentration of 100 μg/ml. Most preferably,BSA is not present in the transcription reaction.

Most preferably, the in vitro transcription reaction comprises thefollowing components:

1 μg linearized plasmid DNA

4 mM ATP, CTP and UTP

1.45 mM GTP,

5.8 mM CAP analogue

80 mM HEPES

24 mM MgCl₂

2 mM Spermidine

40 mM DTT

5 u pyrophosphatase

4 u RNase inhibitor

100 u T7 RNA polymerase

The in vitro transcription reaction is preferably incubated at 37° C.,more preferably for at least 4 hours.

Purification of the In Vitro Transcribed RNA:

Removal of Template DNA:

The template DNA is preferably removed from the in vitro transcription,e.g., the DNA template is separated from the RNA transcript. In oneembodiment, the RNA transcript is removed chromatographically using apolyA capture, e.g., oligo dT, based affinity purification step. The RNAtranscript binds affinity substrate, while the DNA template flow throughand is removed.

In one embodiment, the polyA capture based affinity purification isoligo dT purification. For example, a polythymidine ligand isimmobilized to a derivatized chromatography resin. The mechanism ofpurification involves hybridization of the polyA tail of the RNAtranscript to the oligonucleotide ligand. The DNA template will notbind. In addition, RNA transcripts that do not contain PolyA stretches(short aborts and other truncates formed during in vitro transcription)will not bind to the resin and will not form a duplex with the affinityligand. Polyadenylated RNA can then be eluted from the resin utilizing alow ionic strength buffer or a competitive binding oligonucleotidesolution. A one pot purification method can yield highly purified poly Acontaining RNA with recoveries >80% actively removes endotoxin, DNAtemplate, and enzymes utilized in the production of RNA using a simplecapture and elute methodology with no subsequent fraction of capturedpoly A containing RNA. This purification increases mRNA product purityand in turn significantly increases target protein expression.

Particularly preferred is the enzymatic removal of DNA template usingDNAse I.

Following transcription, the DNA template can be removed using methodsknown in the art comprising DNase I digestion. Such step additionallyremoves residual bacterial genomic DNA.

In this context, it is particularly preferred to add 6 μl DNAse I (1mg/ml) and 0.2 μl CaCl₂ solution (0.1 M)/μg DNA template to thetranscription reaction, and to incubate it for at least 3 h at 37° C.

Enzymatic Capping:

In a preferred embodiment, the RNA obtained by the inventive method mayfurther be capped. As an alternative to co-transcriptional capping usingCAP analogs, the RNA may be capped enzymatically.

Capping may be performed either before or after purification of the RNAtranscript.

For large scale manufacturing, 5′ capping of RNA transcripts istypically performed using a chemical cap analog. This is performedco-transcriptionally where the cap analog: GTP molar ratio in thereaction is ˜4:1. This typically results in −80% capping efficiency, aswell as reduced RNA transcript yields due to consumption of GTP. Thishigh abundance of uncapped species is undesirable when developingtherapeutic RNA. Since only capped mRNA is translated into protein, thepresence of a high abundance of uncapped species (ie 20%) is problematicas efficacy (protein production/mg RNA) is reduced by 20%> and 20%> ofthe final drug substance is an inert impurity, decreasing processproductivity.

In a preferred embodiment, following RNA purification (e.g. LiClprecipitation), a 5′ Cap can enzymatically added to the RNA transcript(if no Cap analog has been used in the in vitro transcription mix).

Optionally, recombinant Vaccinia Virus Capping Enzyme and recombinant2′-O-methyltransferase enzyme can create a canonical 5′-5′-triphosphatelinkage between the 5′-terminal nucleotide of an RNA and a guanine capnucleotide wherein the cap guanine contains an N7 methylation and the5′-terminal nucleotide of the RNA contains a 2′-O-methyl. Such astructure is termed Cap1 structure.

In a preferred embodiment, a natural Cap0/Cap1 structure ispost-transcriptionally added to the RNA using vaccinia virus cappingenzyme, (and potentially 2′-O-Methyltransferase) GTP and the Methyldonor SAM in suitable buffer conditions.

Kits comprising capping enzymes are commercially available (e.g.ScriptCap™ Capping Enzyme and ScriptCap™ 2′-O-Methyltransferase (bothfrom CellScript)). Therefore, the RNA transcript is preferably treatedaccording to the manufacturer's instructions.

In a preferred embodiment, RNA dissolved in WFI is first denatured at65° C. for 10 minutes and then placed on ice. A capping reaction mixtureis then prepared containing 0.6 g/l RNA, 1 mM GTP, 0.5 mMS-adenosyl-methionine (SAM), 0.4 units/μl Capping Enzyme, 4 units/μl2′-O-Methyltransferase, 0.05 M Tris-HCl (pH 8.0), 6 mM KCl and 1.25 mMMgCl2 and added to the RNA. The capping reaction mixture is incubated at37° C. for 60 min, adding a Cap1 to the RNA transcript.

Alternatively, only Capping Enzyme (without 2′-O-Methyltransferase) canbe used to generate Cap0 structures.

The capping reaction is followed by precipitation or purification of theRNA transcript, preferably as described herein.

Enzymatic Polyadenylation:

In particular embodiments, the RNA obtained by the inventive method mayfurther be polyadenylated.

Enzymatic Polyadenylation can be performed either before or afterfurther purification of the RNA transcript.

The RNA transcript is incubated with a bacterial poly (A) polymerase(polynucleotide adenylyltransferase) e.g., from E. coli together withATP in the respective buffers. The poly (A) polymerase catalyzes thetemplate independent addition of AMP from ATP to the 3′ end of RNA.

In a preferred embodiment the RNA transcript is reacted with E. colipoly(A) polymerase (e.g. from Cellscript) using 1 mM ATP at 37° C. forat least 30 min. Immediately afterwards, the RNA is purified accordingto the purification methods as described herein (e.g. LiClpurification). RNA is run on an agarose gel to assess RNA extension asdescribed herein under section ‘B. Quality Control 2’.

Quality Control: Size Determination of Poly-A-Tail

Determination of the Poly-A-Tail Length Via polyA Binding Protein Assay:

The poly(A) length is preferably determined in units of or as a functionof polyA binding protein binding. In this embodiment, the polyA tail islong enough to bind at least 4 monomers of polyA binding protein. PolyAbinding protein monomers bind to stretches of approximately 38nucleotides. As such, it has been observed that polyA tails of about 80nucleotides and 160 nucleotides are functional.

Other Poly(A) Tail Assays:

Three methods for measuring the length of a poly(A) tail are presentedherein as exemplary methods: the poly(A) length assay, theligation-mediated poly(A) test (LM-PAT), and the RNase H assay. Thefirst two methods are PCR-based assays involving cDNA synthesis from anoligo(dT) primer. The third method involves removing the poly(A) tailfrom the mRNA of interest. A major obstacle to studying the enzymaticstep of mammalian mRNA decay has been the inability to capture mRNAdecay intermediates with structural impediments such as the poly(G)tract used in yeast. To overcome this, we combined a standard kineticanalysis of mRNA decay with a tetracycline repressor-controlled reporterwith an Invader RNA assay. The Invader RNA assay is a simple, elegantassay for the quantification of mRNA. It is based on signalamplification, not target amplification, so it is less prone toartifacts than other methods for nucleic acid quantification. It is alsovery sensitive, able to detect attomolar levels of target mRNA. Finally,it requires only a short sequence for target recognition andquantitation. Therefore, it can be applied to determining the decaypolarity of a mRNA by measuring the decay rates of different portions ofthat mRNA.

Purification of In Vitro Transcribed RNA:

In a particularly preferred embodiment, the inventive method comprisesat least one step of purifying the RNA obtained by in vitrotranscription in step b) of the inventive method. In the following,exemplary purification steps are described, which may be used inpreferred embodiments of the invention.

RNA purification may include any purification method known in the artsuch as alcohol precipitation, chromatography, or LiCl precipitation.

LiCl Precipitation:

LiCl precipitation is particularly preferred.

High-molar LiCl solution is added to specifically precipitate the RNAtranscript. Following precipitation the RNA transcript is re-suspendedin water for injection.

LiCl precipitation is preferably performed by adding 50% of the volume8M LiCl. The reaction is mixed and incubated at room temperature.Subsequently the reaction is centrifuged, the supernatant discarded andthe RNA pellet washed with 75% ethanol. After drying, the RNA ispreferably resuspended in water.

This step also further ensures the removal of proteins from previousmanufacturing steps, including E. coli proteins, restriction enzymes,RNA polymerase, RNase inhibitor, DNase I, and BSA. Moreover, theRNA-specific precipitation also removes contamination with residualplasmid DNA and bacterial (genomic) DNA.

Purification by HPLC

According to another embodiment, the purification of the RNA transcriptby HPLC is particularly preferred.

HPLC (abbreviation for “High Performance (High Pressure) LiquidChromatography”) is an established method of separating mixtures ofsubstances, which is widely used in biochemistry, analytical chemistryand clinical chemistry. An HPLC apparatus consists in the simplest caseof a pump with eluent reservoir containing the mobile phase, a sampleapplication system, a separation column containing the station-aryphase, and the detector. In addition, a fraction collector may also beprovided, with which the individual fractions may be separatelycollected after separation and are thus available for furtherapplications.

Reversed phase HPLC consists of a non-polar stationary phase and amoderately polar mobile phase. One common stationary phase is e.g.silica, which has been treated with RMe₂SiCl, where R is a straightchain alkyl group such as C₁₈H₃₇ or C₈H₁₇. The retention time istherefore longer for molecules, which are more non-polar in nature,allowing polar molecules to elute more readily. Retention time isincreased by the addition of polar solvent to the mobile phase anddecreased by the addition of more hydrophobic solvent.

The product RNA can be purified from various contaminations fromprevious manufacturing steps. These include buffer contaminations,protein impurities (Escherichia coli proteins, Restriction enzymes,T7-RNA-Polymerase, RNase-Inhibitor, DNase I, and BSA), impurities fromRNA-RNA hybrids, from DNA-RNA hybrids or their fragments, from pDNAcontaminations and bacterial genomic DNA contaminations, and solventcontaminations (Acetonitrile, Chloroform, TEAA, 2-Propanol and Phenol)and free nucleotides.

Moreover, size exclusion occurs during that procedure (smaller andlarger RNAs can be excluded).

The RNA obtained in step b) of the inventive method is preferablypurified by a size-selective HPLC based technique. Moreover, it allowsmonitoring structural and size heterogeneity. The purified mRNA ispreferably concentrated by alcohol precipitation and re-suspended inwater for injection.

Particularly preferred is a RP-HPLC method as described in WO2008077592,which preferably comprises the following components:

PLRP-S 4000 Â 8 μm 50×25 mm column

crosslinked macroporous poly(styrene/divinylbenzene) reversed phasepacking

Reagents:

Eluent A (100 mM Triethylammoniumacetat in WFI, pH 7.0 (+/−0.5))

Eluent B (100 mM Triethylammoniumacetat in 25% acetonitrile, pH 7.0(+/−0.5))

1M Triethylammoniumacetat

Alternatives for (Common) HPLC: Ion/Anion Exchange HPLC

AEX chromatography is an alternative method of purification thatleverages ionic interaction between positively charged sorbents andnegatively charged molecules. AEX sorbents typically include a chargedfunctional group cross-linked to solid phase media. Ion exchangechromatography for preparative RNA transcript also provides a solutionthat allows for separations of longer RNA transcripts, including lengthsof up to at least 10,000 nucleotides. In addition, the methods allow forseparations of chemically modified RNA transcripts (WO2014144767A1).

A sample comprising the RNA transcript is preferably contacted with anion exchange sorbent comprising a positively-charged functional grouplinked to solid phase media, and the sample is delivered with at leastone mobile phase, where the RNA transcript in the sample binds thepositively-charged functional group of the ion exchange sorbent. In oneembodiment, the sample is delivered under denaturing conditions, forexample, the sample can be contacted with urea. In other embodiments,the mobile phase is a Tris-EDTA-acetonitrile buffered mobile phase, orthere are two mobile phases made of Tris-EDTA-acetonitrile. In otherembodiments, the mobile phase comprises a chaotropic salt, such assodium perchlorate. The ion exchange sorbent elutes a portion of thesample comprising the RNA transcript and one or more separate portionsof the sample comprising any impurities. At least one aspect of theportion of the sample comprising the RNA transcript and the separateportions of the sample comprising the impurities are then analyzed,where the aspect is charge heterogeneity of the RNA transcript, massheterogeneity of the RNA transcript, process intermediates, impurities,or degradation products. The RNA transcript is then characterized byusing the analysis to determine the charge heterogeneity of the RNAtranscript.

Affinity Purification (Oligo-dT)

In one embodiment, the poly A capture based affinity purification isoligo dT purification. For example, a polythymidine ligand isimmobilized to a derivatized chromatography resin. The mechanism ofpurification involves hybridization of the poly A tail of the RNAtranscript to the oligonucleotide ligand. The DNA template will notbind. In addition, RNA transcripts that do not contain Poly A stretches(short aborts and other truncates formed during in vitro transcription)will not bind to the resin and will not form a duplex with the affinityligand. Poly adenylated RNA can then be eluted from the resin utilizinga low ionic strength buffer or a competitive binding oligonucleotidesolution. A one pot purification method can yield highly purified poly Acontaining RNA with recoveries >80% actively removes endotoxin, DNAtemplate, and enzymes utilized in the production of RNA using a simplecapture and elute methodology with no subsequent fraction of capturedpoly A containing RNA. This purification increases mRNA product purityand in turn significantly increases target protein expression.

Hydroxyapatite Chromatography

Purification of RNA transcript is described in WO2014140211.

Hydroxyapatite chromatography involves hydroxyapatite as stationaryphase. Hydroxyapatite is a form of calcium phosphate having the chemicalformula Ca₅(P0₄)₃(OH). Hydroxyapatite chromatography of nucleic acids isbelieved to exploit the charge interaction between their negativelycharged phosphate backbone and the positively charged calcium ions onthe surface of the hydroxyapatite medium. Differential elution {e.g. toseparate protein, DNA and undesired RNA species from desired RNAspecies) is accomplished by the application of an increasing phosphategradient. Phosphate ions present in the buffer compete with thephosphate groups of the retained nucleic acid species for calcium on thehydroxyapatite medium, thus allowing separation by selective elution ofmolecules. In this mixed mode chromatography, the binding is a balanceof attraction of the RNA phosphate backbone to the calcium ions of thehydroxyapatite medium and repulsion of the RNA phosphate backbone fromthe phosphate of the hydroxyapatite medium. Compared to ion exchangechromatography, the strength of the binding on a hydroxyapatite mediumis dependent on charge density rather than total charge. This importantdifference allows for the separation of molecules upon their chargedensity (e.g. RNA vs DNA vs proteins) and the binding and elution of RNAregardless of its total charge, and therefore regardless of its length.Therefore this method can be used for the purification of RNA moleculesof any length. The fractionation of nucleic acids using hydroxyapatitewas described in the 1960s (Bernardi et al. 1965). This approach hasbeen exploited for applications including isolation and separation ofviral RNA, dsDNA and ssDNA from environmental samples (Andrews-Pfannkochet al. 2010), separation of DNA and RNA from tissue-extracted nucleicacids (Beland et al. 1979) and separation of DNA for hybridizationstudies (Kamalay et al. 1984).

Core Bead Chromatography (does not Require Prior DNA Digest)

Purification of RNA transcript by core bead chromatography is describedin WO 2014140211A1.

Preferably, RNA is selectively recovered from the column in theflow-through. Proteins and short nucleic acids are retained in thebeads. Flow-through fractions containing RNA may be identified bymeasuring UV absorption at 260 nm. The composition comprising the RNA ofinterest collected in the flow-through is highly purified relative tothe preparation before the core bead chromatography step. Multipleeluted fractions containing the RNA of interest may be combined beforefurther treatment. An exemplary core bead flow-through chromatographymedium is Capto™ Core 700 beads from GE Healthcare. Suitablechromatography setups are known in the art, for example liquidchromatography systems such as the AKTA liquid chromatography systemsfrom GE Healthcare.

Parameters can be set in a way that pDNA and proteins are captured inthe beads, and RNA products flow through. Afterwards, HPLC purificationcan be conducted to get rid of RNA fragments etc.

Alternatively or additionally the RNA is recovered by other purificationmethods (e.g. affinity chromatography, size exclusion chromatography,anion exchange chromatography, etc.)

In one embodiment purification of the RNA transcript by LiClprecipitation, RP-HPLC using a crosslinked macroporouspoly(styrene/divinylbenzene) reversed phase and subsequent isopropanolprecipitation using Na⁺ as monovalent cation is particularly preferred.

Lyophilization of the Purified RNA Transcript:

In a particularly preferred embodiment, the RNA transcript islyophilized after purification by any lyophilization method known in theart. Lyophilization of the RNA transcript particularly increases thehalf-life of the RNA.

Resuspension of Lyophilized RNA and Adjustment of the RNA Concentration:

The resuspension is preferably performed using the respective amount ofWFI-water (water for injection) or pyrogen free water at RT. The finalconcentration is set, and the medicament is sterile-filtered, preferablythrough a pore size 0.22 μm, for bioburden reduction. A sample of theproduced RNA solution is used for photometric determination of the RNAcontent. Eventually, the RNA-solution is sterile filtered. For long-termstorage, the sterile-filtered, concentration-adjusted RNA solution isstored at −80° C.

The RNA solution is resuspended in a concentration of 0.1-50 g/l, morepreferably in a concentration of 1-20 g/l, more preferably in aconcentration of 1-10 g/l and most preferably in a concentration of 5g/l.

B. Quality Control 2

In the following section (section B and subsections), preferred stepsare described for controlling the quality of the RNA obtained by theinventive method. Any of the steps described herein may be applied toany quality control carried out at any stage of the method. Preferably,the steps may independently be applied to the final RNA product as wellas to intermediates (such as the raw RNA obtained in the in vitrotranscription reaction). In particular, this section relates topreferred steps for determination of RNA identity, determination of RNAintegrity and/or determination of the purity of the RNA preparation.

B.1 Determination of the RNA Concentration/RNA Content/RNA Amount

The RNA content is preferably determined by spectrometric analysis.

Spectrophotometric analysis is based on the principles that nucleicacids absorb ultraviolet light in a specific pattern. In the case of DNAand RNA, a sample that is exposed to ultraviolet light at a wavelengthof 260 nanometers (nm) will absorb that ultraviolet light. The resultingeffect is that less light will strike the photodetector and this willproduce a higher optical density (OD).

An optical density of 1 measured at 260 nm corresponds to aconcentration of 40 μg/ml single stranded RNA.

The yield of the test transcription is evaluated measurement of theabsorption at 260 nm (OD260).

B.2 Determination of RNA Identity

B.2.1 Determination of Transcript Length and Transcript Uniqueness

The correct transcript length and transcript uniqueness is preferablyconfirmed in order to verify identity and purity of the RNA obtained instep b) of the inventive method.

The band uniqueness and band size of mRNA is preferably analyzed byagarose gel electrophoresis, capillary gel electrophoresis,polyacrylamide gel electrophoresis or HPLC. Particularly preferred isagarose gel electrophoresis.

Electrophoresis through agarose gels is a method to separate RNA. TheRNA can be determined in the agarose gel by addition of the fluorescentintercalating dye ethidium bromide or other commercially available dyes(SybrSafe DNA stain, Cybr Green, Orange DNA loading dye)

As running usually 1×MOPS buffer is used (MOPS, 0.74% Formaldehyde, inultra-pure water)

For the preparation of the agarose gel, 0.5-3% (w/v) agarose or morepreferably 1.2% (w/v) agarose is melted in 1× running buffer.

The solution is poured into a mold and allowed to harden. When anelectric field is applied across the gel, RNA, which is negativelycharged, migrates to the anode. As running buffer the same buffer asused for preparation of the agarose gel is used.

Loading buffer (e.g. Gel loading buffer with ethidium bromide (10 mg/l))is added to the sample and loaded on the agarose gel. After gel runningthe RNA can be determined, for example, by ultraviolet light. The RNAlength can be compared to the predicted length and therefore allows thedetermination if the correct DNA sequence encoding the target RNAsequence is integrated into the plasmid.

Alternatively, polyacrylamide gel electrophoresis, capillary gelelectrophoresis, or HPLC may be used.

B.2.2 Determination of RNA Identity by RNAse Treatment with SubsequentAnalysis of the Degraded Product

In a preferred embodiment, RNA identity is confirmed by a test, whichuses RNAse A digestion of a sample of the RNA obtained in step b) of theinventive method. The digested RNA is preferably compared with anuntreated sample on an RNA gel electrophoresis.

In this context, it is particularly preferred to digest 1 μg RNAtranscript with 10 μg RNAse A.

B.2.3 Determination of RNA Identity by RT-PCR with Subsequent Analysisof the Product Via-Agarose Gelelectrophoresis

In a first step, the RNA is preferably converted into complementary DNA(cDNA) using the enzyme reverse transcriptase. In a second step, theresulting cDNA is amplified via PCR (polymerase chain reaction) usingappropriate primers to provide a PCR product of a certain size. The PCRproduct is analyzed via agarose gel electrophoresis for correct bandsize.

RT-PCR using the RNA as a template is preferably used to determine thesize of the RNA product. For reverse transcription, kits arecommercially available.

Afterwards, produced cDNA is amplified with target-specific primers andproduct band sizes are analysed in a conventional DNA agarose gelelectrophoresis, preferably as described in the context of QualityControl 1.

B.2.4 Determination of RNA Identity by Reverse Transcription Sequencing:

The RNA transcript can be characterized by reverse transcriptionsequencing. The RNA product is incubated with a common reversetranscriptase, a set of primers, and dNTPs to obtain cDNA samples. ThecDNA serve as a template for PCR to amplify the cDNA. The PCR product isthen characterized by analysis using a sequencing procedure as definedherein such as Sanger sequencing or bidirectional sequencing.

B.2.5 Determination of RNA Identity by Oligonucleotide Mapping:

The RNA obtained in step b) of the inventive method is preferablyincubated with various nucleotide probes under conditions sufficient toallow hybridization of the probes to the RNA to form duplexes, whereeach of the nucleotide probes includes a sequence complementary to adifferent region of the RNA transcript.

The formed duplexes are then contacted with an RNase (such as RNase H orRNase TI) under conditions sufficient to allow RNase digestion of theduplexes to form reaction products.

Next, the reaction products are analyzed, for example by using aprocedure such as reverse phase high performance liquid chromatography(RP-HPLC), anion exchange HPLC (AEX), or RP-HPLC coupled to massspectrometry (MS). Finally, the RNA is characterized by using theanalysis of the reaction products to determine the sequence of the RNA.

B.2.6 Determination of RNA Identity by RNA Sequencing.

In a preferred embodiment, the identity of the RNA may be determined byRNA sequencing. Methods for RNA sequence analysis are known in the artand may be used herein.

B.3 Determination of RNA Integrity

The relative integrity of the RNA obtained in step b) of the inventionis preferably determined as the percentage of full-length RNA (i.e.non-degraded RNA) with respect to the total amount of RNA (i.e.full-length RNA and degraded RNA fragments (which appear as smears ingel electrophoresis)).

B.4 Determination of pH

Potentiometric determination of the pH content using a conventionalvolt-meter, according to the european pharmacopedia (PhEur) 2.2.3 ispreferably used to determine the pH value in the RNA preparation.

B.5 Determination of Osmolality

In a preferred embodiment, the osmolality of the RNA obtained in step b)of the inventive method is determined. The measurement of the osmolalityis performed using a conventional osmometry device according to PhEur2.2.35.

B.6 Determination of Bioburden/Microbial Content

To determine sterility of the RNA preparation, an RT-PCR using universalbacterial primers (detecting universal occurring genes in bacteria) maybe performed. Moreover, a plating assay may be conducted.

Particularly preferred is a plating assay according to PhEur 2.6.12.:

For determination of the bioburden the presence/absence of bacteria istested under aerobe and anaerobe conditions after plating the RNA onagar- and/or glucose plates and incubation for several days (e.g. 5 and7 days, respectively). The bioburden is assessed by counting thebacteria clones grown on bacteria plates.

For this purpose, different media for plating can be used. Tryptic SoyAgar (TSA) (Soybean Casein Digest Agar (CSA)) and Sabouraud Glucose (2%)Agar plates are particularly preferred.

B.7 Determination of Endotoxin Contamination:

A test for bacterial endotoxins is preferably used to detect or quantifyendotoxins of gram-negative bacterial origin by using amoebocyte lysatefrom horseshoe crab (Limulus polyphemus or Tachypleus tridentatus). Theprinciple has been discovered by Levin (Levin, J. 1979. The reactionbetween bacterial endotoxin and amebocyte lysate, p. 131-146. In E.Cohen (ed.), Biomedical Applications of the Horseshoe Crab (Limulidae),Progress in Clinical and Biological Research, Vol. 29. Alan R. Liss,Inc., New York).

In general, there are 3 techniques for performing this test: thegel-clot technique, which is based on gel formation; the turbidimetrictechnique, based on the development of turbidity after cleavage of anendogenous substrate; and the chromogenic technique, based on thedevelopment of colour after cleavage of a synthetic peptide-chromogencomplex

Preferred is the LAL-test. The amount of endotoxins per volume of RNA isdetermined and evaluated via kinetic-turbidometric LAL(Limulus-Amoebocyte-Lysate) test according to Ph. Eur. 2.6.14(Pharmacopoea Europaea).

B.8 Determination of Protein Contamination:

The total protein content per volume of RNA obtained in step b) of theinventive method is calculated.

Several different methods in the art are known for detection of protein,including UV absorbance measurements at 280 nm (due to the presence ofaromatic amino acids), the Lowry assay, the Biuret assay, the Bradfordassay, and the BCA (Bichinonic Acid) assay.

The BCA (Bichinonic Acid) assay, a colorimetric method of detectionbased on complexation of proteins with copper and BCA. The total proteinconcentration contained in the RNA is measured via absorption at 562 nmcompared to a protein standard (BSA). The principle of the bicinchoninicacid (BCA) assay is similar to the Lowry procedure (Lowry, O. H. et al,J. Biol. Chem., 193, 265-275 (1951)). Both rely on the formation of aCu²⁺-protein complex under alkaline conditions, followed by reduction ofthe Cu²⁺ to Cu⁺. The amount of reduction is proportional to the proteinpresent. It has been shown that cysteine, cystine, tryptophan, tyrosine,and the peptide bond are able to reduce Cu²⁺ to Cu⁺. BCA forms apurple-blue complex with Cu⁺ in alkaline environments, thus providing abasis to monitor the reduction of alkaline Cu²⁺ by proteins atabsorbance maximum 562 nm.

Another method which could be used for the determination of protein isthe Bradford method. The Bradford assay, a colorimetric protein assay,is based on an absorbance shift of the dye Coomassie Brilliant BlueG-250 in which under acidic conditions the red form of the dye isconverted into its bluer form to bind to the protein being assayed. The(bound) form of the dye has an absorption spectrum maximum historicallyheld to be at 595 nm. The cationic (unbound) forms are green or red. Thebinding of the dye to the protein stabilizes the blue anionic form. Theincrease of absorbance at 595 nm is proportional to the amount of bounddye, and thus to the amount (concentration) of protein present in thesample.

Particularly preferred is the BCA assay. For performing a BCA assay,several commercially available kits may be used.

B.9 Determination of Plasmid DNA Contamination:

Residual plasmid DNA may optionally be detected by PCR or quantitativePCR as described herein using specific primers and probes for DNAplasmid used for in vitro transcription. Particularly preferred is thedetection of residual plasmid DNA via quantitative PCR as describedherein using specific primers and probes for the ampicillin gene hostedin the production vector. The probes are used as positive control andthus for calculation of the plasmid DNA concentration.

The use of following primers and probes are particularly preferred:

(SEQ ID NO: 12) Sense-Primer bla13U: GATACCGCGAGACCCAC  (SEQ ID NO: 13)Antisense-Primer bla355L: GGAACCGGAGCTGAATG  (SEQ ID NO: 14)Probe BL04FL: GCCAGCCGGAAGGGCC-FL  (SEQ ID NO: 15)Probe BL04LC: LC Red640-GCGCAGAAGTGGTCCTGCA-Ph B.10 Determination of Bacterial DNA Contamination:

Residual bacterial DNA may optionally be detected e.g. by PCR orquantitative PCR using specific primers and probes for bacterial genomicsequences. Particularly preferred is the detection of residual bacterialDNA is detected via quantitative PCR using specific primers and probesfor the E. coli gene uidA. The probes are preferably used as positivecontrol and thus for calculation of the bacterial DNA concentration.

The following primers and probes are preferably used for thequantitative PCR:

(SEQ ID NO: 8) Primer EC 679U: GGACAAGGCACTAGCG  (SEQ ID NO: 9)Primer EC 973 L: ATGCGAGGTACGGTAGGA  (SEQ ID NO: 10)Probe EC1 FL: CATCCGGTCAGTGGCAGT-FL  (SEQ ID NO: 11)Probe EC1 LC: LC640-AAGGGCGAACAGTTCCTGA-ph B.11 Determination of Residual Solvent Contamination

Residual solvents are preferably analyzed based on the PhEur 2.2.28method via headspace gas chromatography using the standard additionmethod. Samples are heated to 80° C., equilibrated, and the gas phase isinjected and analyzed using FID (flame ionization detection).

The analysis preferably includes acetonitrile, chlorophorm,triethylammonium acetate (TEAA), isopropanol, and phenol.

In the following section, the present invention is further illustratedby particularly preferred embodiments, which are preferablycharacterized by the features as described in the following, wherein anyone of said features may be combined with any other feature describedherein.

According to a preferred embodiment, step a) of the inventive methodcomprises at least one of the following steps A) to K):

-   A) selection of a RNA sequence (to be produced by in vitro    transcription);-   B) reverse transcription of the target RNA sequence;-   C) synthesis of a plasmid template DNA comprising a nucleic acid    sequence encoding the RNA sequence;-   D) quality control of the plasmid template DNA: determination of the    identity of the nucleic acid sequence encoding the RNA sequence;-   E) transformation of the plasmid template DNA into bacteria;-   F) fermentation;-   G) quality control of the plasmid template DNA: yield estimation of    the plasmid template DNA and determination of the identity of the    nucleic acid sequence encoding the RNA sequence;-   H) plasmid template DNA isolation (giga preparation)-   I) quality control of isolated plasmid template DNA: determination    of the identity of the nucleic acid sequence encoding the RNA    sequence and determination of the purity of the plasmid template DNA    preparation;-   J) linearization of plasmid template DNA;-   K) quality control of linearized plasmid template DNA, e.g.    completeness of linearization, estimation of RNA yield and    determination of RNA identity.

In a further preferred embodiment, step a) of the inventive methodcomprises the steps A) to K) as defined above, preferably inalphabetical order.

Preferably, step a) of the inventive method comprises a step I) asdefined above, wherein the step I) comprises at least one of

-   -   i) photometric determination of the plasmid template DNA        content;    -   ii) determination of RNA contaminations;    -   iii) determination of the identity of the nucleic acid sequence        encoding the RNA sequence by restriction analysis of the test        plasmid isolation    -   iv) determination of the identity of the nucleic acid sequence        encoding the RNA sequence by sequencing of the insert DNA        sequence    -   v) determination of the presence and/or the amount of an        endotoxin;    -   vi) determination of protein content;    -   vii) determination of bioburden; and    -   viii) determination of bacterial DNA.

In addition or alternatively, step a) of the inventive method maycomprise a step K) as defined above, wherein the step K) comprises atleast one of

-   -   i) control of linearization;    -   ii) determination of RNA identity in test in vitro transcription        by agarose gel electrophoresis; and/or    -   iii) determination of RNAse contaminations in linearized plasmid        template DNA;

It is further preferred that step b) of the inventive method comprisesat least one of the following steps L) to P)

-   L) in vitro transcription;-   M) first purification of the in vitro transcribed RNA by    precipitation, preferably LiCl-precipitation;-   N) quality control of the in vitro transcribed RNA: determination of    RNA identity-   O) second purification of the in vitro transcribed RNA by    preparative RP-HPLC and precipitation-   P) quality control of the in vitro transcribed RNA: determination of    RNA identity and RNA integrity,    wherein the identity and/or the integrity of the RNA are preferably    determined via gel electrophoresis, more preferably agarose gel    electrophoresis.

According to a particular embodiment, the inventive method comprises astep Q), which comprises lyophilization of the in vitro transcribed RNA,resuspension of the freeze-dried RNA and sterile filtration of theresuspended RNA. Preferably, the sterile filter used in step Q) istested by carrying out a bubble-point test. More preferably, the RNAyield is determined photometrically after resuspending the RNA.

In another preferred embodiment, the inventive method comprisescontrolling the quality of the (final) product RNA by at least one stepselected from the following steps i) to xi)

-   -   i) determination of RNA identity by RNAse digestion;    -   ii) determination of RNA identity by RT-PCR;    -   iii) determination of RNA identity and RNA integrity by agarose        gel electrophoresis;    -   iv) determination of pH;    -   v) determination of osmolality;    -   vi) determination of bioburden;    -   vii) determination of endotoxins;    -   viii) determination of protein content;    -   ix) determination of plasmid template DNA;    -   x) determination of bacterial DNA and/or    -   xi) determination of the presence and/or the amount of an        organic solvent (acetonitrile, chloroform, triethylammonium        acetate (TEAA), isopropanol, and phenol).

More preferably, all of steps i) to xi) as defined above are employed,preferably in numerical order.

In a particularly preferred embodiment, the inventive method comprisesthe following steps:

-   A) selection of a RNA sequence (to be produced by in vitro    transcription);-   B) reverse transcription of the target RNA sequence;-   C) synthesis of a plasmid template DNA comprising a nucleic acid    sequence encoding the RNA sequence;-   D) quality control of the plasmid template DNA: determination of the    identity of the nucleic acid sequence encoding the RNA sequence    -   i) by restriction analysis and/or    -   ii) by sequencing of the nucleic acid sequence encoding the RNA        sequence;-   E) transformation of the plasmid template DNA into bacteria;-   F) fermentation;-   G) quality control of the plasmid template DNA: yield estimation of    the plasmid template DNA and determination of the identity of the    nucleic acid sequence encoding the RNA sequence;    -   i) test plasmid template DNA isolation (mini preparation) and        photometric determination of the plasmid template DNA content to        estimate yield of plasmid template DNA and/or    -   ii) determination of the identity of the nucleic acid sequence        encoding the RNA sequence by restriction analysis of the test        plasmid isolation-   H) plasmid template DNA isolation (giga preparation)-   I) quality control of isolated plasmid template DNA: determination    of the identity of the nucleic acid sequence encoding the RNA    sequence and determination of the purity of the plasmid template DNA    preparation    -   i) photometric determination of the plasmid template DNA        content;    -   ii) determination of RNA contaminations;    -   iii) determination of the identity of the nucleic acid sequence        encoding the RNA sequence by restriction analysis of the test        plasmid isolation    -   iv) determination of the identity of the nucleic acid sequence        encoding the RNA sequence by sequencing of the insert DNA        sequence    -   v) determination of the presence and/or the amount of an        endotoxin;    -   vi) determination of protein content;    -   vii) determination of bioburden; and/or    -   viii) determination of bacterial DNA-   J) linearization of plasmid template DNA;-   K) quality control of linearized plasmid template DNA, e.g.    completeness of linearization, estimation of RNA yield and    determination of RNA identity:    -   i) control of linearization;    -   ii) determination of RNA identity in test in vitro transcription        by agarose gel electrophoresis; and/or    -   iii) determination of RNAse contaminations in linearized plasmid        template DNA;-   L) in vitro transcription;-   M) first purification of the in vitro transcribed RNA by    precipitation, preferably LiCl-precipitation;-   N) quality control of the in vitro transcribed RNA: determination of    RNA identity    -   i) determination of RNA identity by agarose gel electrophoresis;-   O) second purification of the in vitro transcribed RNA by    preparative RP-HPLC and precipitation-   P) quality control of the in vitro transcribed RNA: determination of    RNA identity and RNA integrity    -   i) determination of the RNA identity and RNA integrity by        agarose gel electrophoresis;-   Q) lyophilization of the in vitro transcribed RNA, resuspension of    the freeze-dried RNA and sterile filtration of the resuspended RNA;-   R) quality control: determination of the RNA yield    -   i) photometric determination of RNA content and/or    -   ii) bubble-point-test for control of the sterile filter;-   S) end-product-control: Determination of RNA identity, RNA integrity    and purity of in vitro transcribed RNA:    -   i) determination of RNA identity by RNAse digestion;    -   ii) determination of RNA identity by RT-PCR;    -   iii) determination of RNA identity and RNA integrity by agarose        gel electrophoresis;    -   iv) determination of pH;    -   v) determination of osmolality;    -   vi) determination of bioburden;    -   vii) determination of endotoxins;    -   viii) determination of protein content;    -   ix) determination of plasmid template DNA;    -   x) determination of bacterial DNA and/or    -   xi) determination of the presence and/or the amount of an        organic solvent (acetonitrile, chloroform, triethylammonium        acetate (TEAA), isopropanol, and phenol).

It is particularly preferred that the quality of the plasmid templateDNA obtained in step J) above is controlled by carrying out a test invitro transcription.

BRIEF DESCRIPTION OF THE FIGURES

The figures shown in the following are merely illustrative and shalldescribe the present invention in a further way. These figures shall notbe construed to limit the present invention thereto.

FIGURES

FIG. 1: Schematic overview of the major production steps in an exemplaryprocess.

FIG. 2: Consensus Promoter Sequences (SEQ ID NOs: 4, 5, and 6, as showntop to bottom). The +1 base is the first base incorporated into RNAduring transcription. The underline indicates the minimum sequencerequired for efficient transcription.

FIG. 3: P0361 encoding PpLuc (Photinus pyralis Luciferase).

FIG. 4: Overview of an exemplary process for manufacturing a drugsubstance comprising RNA.

FIG. 5: Plasmid map of P0624(P0624-pCV26-HsKLK3(GC)-muag-A64-N5-C30-histoneSL-N5), which was usedfor RNA production.

FIG. 6: DNA sequence of the nucleic acid sequence encoding the RNA inP0624 (HsKLK3(GC)-muag-A64-N5-C30-histoneSL-N5; SEQ ID NO: 1).

FIG. 7: RNA sequence corresponding to DNA according to SEQ ID NO: 1(R1869; SEQ ID NO: 2).

FIG. 8: Protein sequence corresponding to RNA according to SEQ ID NO: 2(SEQ ID NO: 3).

FIG. 9: Gel image of the plasmid DNA test restriction digestion. Agarosegelelectrophoresis of the plasmid DNA test digest, using a DNA laddergene ruler 1 kb (1), a sample without restriction endonuclease (2),HindIII digestion (3), SpeI digestion (4), EcoRI digestion (5), doubledigest with HindIII/SpeI (6), double digest with BsrGI/NsiI (7), doubledigest with BsrGI/HindIII (8), and DNA ladder gene ruler 1 kb (9).

FIG. 10: Gel image of the plasmid DNA test restriction digestion.Agarose gelelectrophoresis of the plasmid DNA test-digest, using a DNAladder gene ruler 1 kb (1), a sample without restriction endonuclease(2), HindIII digestion (3), SpeI digestion (4), EcoRI digestion (5),double digest with HindIII/SpeI (6), double digest with BsrGI/NsiI (7),double digest with BsrGI/HindIII (8), and DNA ladder gene ruler 1 kb(9).

FIG. 11: Gel image of the plasmid DNA test restriction digestion.Agarose gelelectrophoresis of the plasmid DNA test-digest, using a DNAladder gene ruler 1 kb (1), a sample without restriction endonuclease(2), HindIII digestion (3), SpeI digestion (4), EcoRI digestion (5),double digest with HindIII/SpeI (6), double digest with BsrGI/NsiI (7),double digest with BsrGI/HindIII (8), and DNA ladder gene ruler 1 kb(9).

FIG. 12: Gel image of the plasmid DNA linearization. Agarosegelelectrophoresis of the plasmid DNA EcoRI digest, using a DNA laddergene ruler 1 kb (1), EcoRI digested plasmid DNA (2). Size of the DNAladder is indicated.

FIG. 13: Determination of the reference RNA. Lane 1: control withoutDNA/RNA; lane 2: empty; lane 3: RNA size ladder; lane 4: reference RNAincubated with linear DNA; lane 5: reference RNA (without DNA).

FIG. 14: Determination of the specific RNA length. Lane 1: negativecontrol; lane 2: empty; lane 3: RNA size ladder; lane 4: RNA product.

FIG. 15: Preparative HPLC—of in vitro transcribed RNA. Exemplarychromatogram of one preparative HPLC run. Product fractions, separatedby vertical lines are numbered from 1-5. Fractions were pooled (pool 1:fraction 1; pool 2: fraction 2-3; pool 3: fraction 4-5).

FIG. 16: RNA identity test via RNase treatment. Lane 1: blind control(without RNA); lane 2: empty; lane 3: RNA size ladder; lane 4: RNAproduct, not treated with RNase; lane 5: RNA product, treated with RNAseA; lane 6: RNA size ladder.

FIG. 17: Agarose gel electrophorese image of the RT-PCR experiment. Aphotograph of the gel was taken, and the size of the respective bandswas determined. Lane 1: DNA ladder gene ruler 1 kb; lane 2: PCR reaction1; lane 3: PCR reaction 2

EXAMPLES

The Examples shown in the following are merely illustrative and shalldescribe the present invention in a further way. These Examples shallnot be construed to limit the present invention thereto.

Example 1: Sequence of the Template DNA Plasmid

P0624 (P0624-pCV26-HsKLK3(GC)-muag-A64-N5-C30-histoneSL-N5) was used forRNA production. The Figures illustrate the respective plasmid map (FIG.5), DNA sequence encoding RNA R1869 (SEQ ID NO: 1; FIG. 6), the RNAsequence corresponding to SEQ ID NO: 1(HsKLK3(GC)-muag-A64-N5-C30-histoneSL-N5; R1869; SEQ ID NO: 2; FIG. 7)and the corresponding protein sequence (SEQ ID NO: 3; FIG. 8).

Example 2: Restriction Analysis of the Initial Plasmid DNA (QK 1-1)

The identity and quality of the initial plasmid DNA was analyzed usingrestriction digest. Restriction analysis with one single restrictionenzyme (HindIII, SpeI and EcoRI):

-   -   1 μl plasmid DNA (1.2 g/l)    -   1.5 μl 10× reaction buffer    -   1 μl restriction enzyme (1 U/μl)    -   11.5 μl WFI (water for injection)

The reaction mix was incubated for 2 h at 37° C.

Restriction analysis with two restriction enzymes (HindIII and SpeI,BsrGI and NsiI, BsrGI and HindIII):

-   -   1 μl plasmid DNA (1.2 g/l)    -   1.5 μl 10× reaction buffer    -   1 μl restriction enzyme 1 (1 U/μl)    -   1 μl restriction enzyme 2 (1 U/μl)    -   10.5 μl WFI (water for injection)

The reaction mix was incubated for 2 h at 37° C.

TABLE 1 Performed restriction enzyme with respective expected band sizesas indicated Restriction endonuclease Expected band size [bp] HindIII3040 SpeI 3040 EcoRI 3040 HindIII and Spe I 2243 and 797 BsrGI and NsiI2837 and 733 BsrGI and HindIII 2307 and 733Agarose Gelelectrophoresis:

Samples were prepared for agarose gelelectrophoresis by adding 3 μl ofDNA loading dye (6× Orange DNA Loading Dye) to each reaction.Band-separation occurred using a common agarose gelelectrophoresismethod. An agarose gel was prepared comprising 0.8 g agarose in 100 ml1×TBE buffer and 3 μl ethidium bromide. As running buffer, 1×TBE bufferwas used. The results are shown in FIG. 9.

Results:

The observed band pattern was in accordance to the theoreticallyexpected pattern (see Table 1).

Example 3: Sequencing of the RNA Coding Region on the Plasmid DNA(QK3-4)

The RNA coding region in the initial plasmid DNA obtained was sequencedwith an ABI3130XL sequencer, using M13-universal primer:5′-CGCCAGGGTTTTCCCAGTCACGAC (SEQ ID NO: 7) and suitable sequencespecific primers.

Results:

3′-UTR: sequence correct

ORF: sequence correct

5′-UTR: sequence correct

Example 4: Transformation

Heat-Shock Transformation

For amplification of plasmid DNA in bacteria, the chemically competentbacteria cells (Escherichia coli DH5a) were defrosted in the fridge (4°C.). After defrosting, 4 ng of the plasmid DNA solution (P0624, pCV26,insert HsKLK3sI(GC), SEQ ID NO: 1) were added to 50 μl of the competentcells, mixed gently, and incubated for 30 minutes at 4° C. Then, cellswere heat-shocked for 20 seconds at 42° C. Following heat shock, cellswere put back to 4° C. for 2 minutes. Then, 900 μl pre-warmed (37° C.)LB-bouillon medium without antibiotics was added to the cells andincubated for 1 hour at 37° C. in a shaking incubator (170 rpm).

Then, 10 μl, 100 μl and 800 μl of the sample were plated on LB agarplates containing 100 μg/ml ampicillin and incubated for 16 hours at 37°C. The number of bacterial colonies was counted on each plate (see Table2). Moreover, plates were inspected for contaminations (e.g., colonyshape, colony color, smell).

Results:

TABLE 2 Manual inspection of agar plates Volume of plated cells Numberof colonies Contaminations  10 μl 3 NO 100 μl 64 NO 800 μl 270 NO

Example 5: Fermentation

Inoculation of First Pre-Culture

One bacterial colony of the transformation (see example above) waspicked and used to inoculate 5 ml LB-Bouillon containing 100 μg/mlampicillin as an antibiotic. The first pre-culture was incubated in a37° C. shaking incubator (170 rpm) for 16 hours.

Inoculation of a Second Pre-Culture

1 ml of the first pre-culture (OD₆₀₀=3.64) was used to inoculate alarger second 50 ml pre-culture and incubated in a 37° C. shakingincubator for 7 hours. 2 ml of the culture were used for determinationof cell-density (OD₆₀₀=2.52).

Fermentation Process

48 ml of the second pre-culture were used to inoculate 81 LB mediumcomprising ampicillin (100 μg/ml) at 37° C. To obtain optimal bacteriagrowth, feeding solution (LB medium comprising ampicillin (100 μg/ml)with 2% glucose) was constantly fed into the fermenter tank. Duringfermentation, standard parameters were precisely regulated andcontinuously monitored (e.g. pH: 7.0, temperature: 37° C.). The celldensity was controlled by photometric determination at 600 nm. Thefermentation procedure was stopped after 21 hours of incubation time.The final volume of the culture was determined to be 11950 ml, with acellular density of OD₆₀₀=4.66. After fermentation, 1 ml of the culturewas taken for quality control and cells were centrifuged at 11,000 rcfat room temperature for 2 minutes. The supernatant was discarded and thecell pellet was stored at −20° C.

Cell Harvest

11950 ml of bacterial culture (OD600=4.66) were split into 7 differentbatches (approximately 1707 ml per batch). The bacterial culture batcheswere spun down at 6000 g for 15 minutes at room temperature, thesupernatant was discarded and the cell pellet was frozen at −20° C.

Example 6: Plasmid Preparation (Mini-Preparation)

The mini-preparation was performed using a Mini Plasmid Kit according tothe manufacturer's instructions. Following that, the content of dsDNAwas determined. The value was used to estimate the total amount of dsDNAproduced during the fermentation.

Photometric Determination of the dsDNA Content:

The concentration of the isolated plasmid DNA (dsDNA) was determined bya standard photometric method for nucleic acids via measurement of theabsorption at 260 nm (OD260). Measurements were performed intriplicates.

Results:

TABLE 3 Values of the photometric determination of dsDNA in the pDNAsample value 1 value 2 value 3 average [μg/μl [μg/μl [μg/μl [μg/μlSample dsDNA] dsDNA] dsDNA] dsDNA] Plasmid DNA 0.1915 0.1923 0.20240.1954 sampleCalculation of the Total Yield of the Fermentation Process:0.1954 μg/μl*50 μl (volume of plasmid DNA preparation)=9.77 μg

The culture volume used for the mini preparation was 1 ml. Therefore, 1ml of bacterial culture contained 9.77 μg plasmid DNA. The expectedtotal plasmid DNA yield of the whole fermentation culture (11.950 ml) istherefore 116752 μg plasmid DNA.

Example 7: Restriction Analysis of the Plasmid DNA Obtained from theMiniprep

To analyze the plasmid DNA obtained from the mini preparation (seeexample above), a test digest using suitable restriction endonucleaseswas performed according to Example 2.

Results:

The obtained band pattern was in accordance to the theoreticallyexpected pattern (see FIG. 10).

Example 8: Plasmid Giga Preparation

The giga-preparation was performed using an Endotoxin-free plasmid DNApurification kit according to the manufacturer's instructions.

Example 9: Determination of the Plasmid DNA Concentration and OD2601280(QK3-1)

Plasmid DNA concentration (dsDNA) of the DNA sample obtained from thegiga preparation was determined photometrically according to Example 6.The measurements were performed in triplicates. Moreover, the OD 260/280value was determined, which is a measure for nucleic acid purity.

Results:

TABLE 4 Values of the photometric determination of dsDNA in the pDNAsample value 1 value 2 value 3 average [μg/μl [μg/μl [μg/μl [μg/μlSample dsDNA] dsDNA] dsDNA] dsDNA] Plasmid DNA 1.0464 1.1077 1.0789 1.08

TABLE 5 Values of the photometric determination of OD_(260/280). value 1value 2 value 3 Sample [OD_(260/280)] [OD_(260/280)] [OD_(260/280)]average Plasmid DNA 1.81 1.82 1.81 1.81

The concentration of the plasmid DNA preparation was determined to be1.08 μg/μl. The total yield of the giga-preparation was 30.24 mg.

Moreover, the OD 260/280 value was determined to be 1.81.

Example 10: Determination of RNA Contamination Using RNAse Treatment

Plasmid DNA was checked for RNA contamination. Therefore the plasmid DNAwas incubated with RNase A. Afterwards the concentration of the purifiedplasmid DNA was determined again and the difference before and afterRNase treatment was calculated. Therefore a sample of the plasmid DNAsolution obtained from the giga preparation was adjusted to aconcentration of 0.4 g/l. Following that, the DNA concentration wasdetermined (dsDNA) photometrically according to Example 6 Themeasurements were performed in triplicates.

Following that, 38 μl of the plasmid DNA solution were incubated with 1μl RNase A (1 g/l) and incubated for 1 h at 37° C. The RNAse treatedsolution was then added on a Sephadex-column to separate nucleotides.After centrifugation at 2000 rpm for 2 minutes, the eluate was used forphotometric determination of the DNA content at 260 nm according toExample 6. The values before and after RNAse treatment were used tocalculate the percentage of DNA in the sample:

Calculation of the percentage of plasmid DNA contained in the plasmidpreparation:

${\%\mspace{14mu}{plasmid}\mspace{14mu}{DNA}} = {\frac{{concentration}\mspace{14mu}{of}\mspace{14mu}{nucleic}\mspace{14mu}{acids}\mspace{14mu}{after}\mspace{14mu}{RNase}\mspace{14mu} A\mspace{14mu}{digestion}}{{concentration}\mspace{14mu}{of}\mspace{14mu}{nucleic}\mspace{14mu}{acids}\mspace{14mu}{before}\mspace{14mu}{RNase}\mspace{14mu} A\mspace{14mu}{digestion}} \times 100\%}$Results:

TABLE 6 Results of the photometric DNA determination value 1 value 2value 3 [μg/μl [μg/μl [μg/μl Sample dsDNA] dsDNA] dsDNA] average Before0.4262 0.4190 0.4095 0.4182 RNase treatment After 0.3921 0.3476 0.37270.3708 RNase treatment. Percentage plasmid DNA: 88.66%

The dsDNA values (in triplicates) are indicated before and aftertreatment with RNase A. The percentage of plasmid DNA was calculated.

The percentage of plasmid DNA was 88.66%.

Example 11: Test Restriction Digestion of pDNA

To analyze the plasmid DNA obtained from the giga-preparation, a testdigest using suitable restriction endonucleases was performed accordingto Example 2 (see Table 1 for expected band sizes and used enzymes; FIG.11).

Example 12: Sequencing of the RNA Coding Region on the Plasmid DNA

The RNA coding region in the plasmid DNA obtained from the gigapreparation was sequenced with an ABI3130XL sequencer, usingM13-universal primer:

(SEQ ID NO: 7) 5′-CGCCAGGGTTTTCCCAGTCACGAC.Results:3′-UTR: sequence correctORF: sequence correct5′-UTR: sequence correct

Example 13: Determination of the Bacterial Endotoxin Level in thePlasmid DNA Solution

Plasmid DNA solution (0.5 g/l) was analysed for bacterial endotoxincontent (expressed as endotoxin units, EU) using the LAL-test(kinetic-turbidimetric method) according to Ph. Eur., 7th Edition,2.6.14.

Result:

The endotoxin value of the plasmid DNA solution was determined to be<0.2 EU/ml.

Example 14: Determination of Protein Contamination in the Plasmid DNASolution

To determine the protein contamination in the plasmid DNA, acommercially available Bradford test and/or BCA-test was used. The testwas performed according to the manufacturer's instructions.

Photometric Determination of Protein Contamination:

The measurements were performed in a standard photometer, using UVcuvettes. The measurements were performed in dublicates per sample(standards and plasmid DNA sample) at 595 nm (Bradford) or 562 nm (BCA).The protein concentration in the plasmid DNA sample was determined usinga BSA standard curve.

Results:

TABLE 7 Results of the OD measurement of the plasmid DNA. Plasmid ODSample DNA OD OD OD average dilution C_(protein) probe Value 1 Value 2average corrected factor [μg/ml] 0 0.262 0.187 0.225 0.056 1 1.6

The respective OD value of the plasmid DNA sample was determined twice,and an average was calculated. The OD value was used to determine theprotein contamination in the sample, using a standard curve.

The protein contamination in the plasmid DNA sample was determined to be1.6 μg/ml.

Example 15: Determination of the Bioburden in the Plasmid DNA SampleUsing a Plate Count Method

For determination of the bioburden, the presence of bacteria was testedunder aerobic or anaerobic conditions after plating the plasmid DNA onagar and glucose plates and incubating the plates for 5 and 7 days,using a plate count method (according to PhEur 2.6.12.).

The bioburden is typically monitored by counting the growth of bacteriaclones/colonies (colonie forming units (CFU)) on bacteria agar platesover a certain timespan. For this purpose, soybean casein digest agar(CSA) and sabouraud glucose (2%) agar plates were prepared. 100 μl ofplasmid DNA were plated on respective agar plates under sterileconditions and incubated at approximately 22° C. (SG, Sabouraud Glucoseplates) or at 32° C. under aerobic or anaerobic conditions (CSA plates).

Results:

TABLE 8 Results of the plate count assay Day 2 Day 5 Day 6 Day 7 CFU CFUCFU CFU Plate ID 1 2 2 Plate ID 2 9 14 Plate ID 3 1 1 1

The plate count assay resulted in the indicated numbers of CFUs.

In total, 17 CFUs were counted after plating 100 μl of plasmid DNAsolution on the respective agar plates, grown under conditions explainedabove

The bioburden of the plasmid DNA solution was therefore 1.7 CFU/ml.

Example 16: Determination of Residual E. coli DNA by Quantitative PCR

Quantitative PCR was performed to determine the contamination withgenomic Escherichia coli DNA. For this purpose the E. coli specific geneuidA was amplified and quantified using a LightCycler qPCR thermocycle(Roche).

The following probes and primers were used in the experiment:

(SEQ ID NO: 8) Primer EC 679U: GGACAAGGCACTAGCG  (SEQ ID NO: 9)Primer EC 973 L: ATGCGAGGTACGGTAGGA  (SEQ ID NO: 10)Probe EC1 FL: CATCCGGTCAGTGGCAGT-FL  (SEQ ID NO: 11)Probe EC1 LC: LC640-AAGGGCGAACAGTTCCTGA-ph Results:

The quantitative PCR determined an E. coli copy number of 281 in 10 pgof the plasmid DNA preparation. This results in an E. coli copy numberof 28.1 per pg plasmid DNA.

Example 17: Linearization of the Plasmid DNA

To generate a linear template DNA for enzymatic RNA in vitrotranscription, plasmid DNA obtained by giga-preparation (see Example 8)was linearized using restriction endonuclease EcoRI.

Plasmid DNA Linearization:

27.5 ml plasmid DNA [1.08 mg/ml], 9 ml EcoRI restriction enzyme [10U/μl], 15 ml 10× restriction buffer and 98.5 ml WFI (water forinjection) were mixed and divided evenly into 6 reactions. The reactionswere incubated for 4 hours at 37° C.

Plasmid DNA Extraction

17.5 ml phenol/chloroform/isoamylalcohol (25/24/1) were added to eachreaction and mixed by vortexing for 5 minutes. Subsequently, thereactions were centrifuged at 3000 rcf at 10° C. for 10 minutes. Theupper aqueous phase of the reaction was carefully transferred to a newreaction tube.

Plasmid DNA Precipitation

17.5 ml isopropyl alcohol was added to each reaction, mixed by vortexingfor 10 seconds, and centrifuged for 60 minutes at 3000 rcf. Thesupernatant was discarded.

DNA pellets were washed with 10 ml ethanol (75%) for 10 minutes at 3000rcf. After discarding the supernatant, the pellets were centrifugedagain (1 minute) and residual ethanol was carefully removed with apipette.

Re-Suspension of DNA

DNA pellets were dissolved in 5 ml WFI each. The six separate sampleswere pooled and used for photometric determination of dsDNA viameasurement of the absorption at 260 nm (OD260) (final volume: 30 ml).

TABLE 9 Photometric determination of the dsDNA content value 1 value 2value 3 average [μg/μl [μg/μl [μg/μl [μg/μl Sample dsDNA] dsDNA] dsDNA]dsDNA] linearized DNA 0.77 0.77 0.76 0.767

The total amount of linearized dsDNA was (0,767 mg/ml*30 ml)=23.01 mg.

Example 18: Determination of the Linearization Quality Via AgaroseGelelectrophoresis

To analyze the quality of the restriction digest, linearized templateDNA was analyzed via agarose gel electrophoresis. The result is shown inFIG. 12.

Result: A complete linearization of the plasmid DNA could be detected byagarose gelelectrophoresis.

Example 19: Test for RNase Contamination of the Linear DNA Template

To test the obtained linear DNA template for RNase contamination, areference RNA molecule was incubated with the linear DNA template.

2 μl RNA reference (RNA R488, expected size 507 bases) were incubatedwith 6 μl linear DNA (concentration adjusted to 0.5 g/l), and 2 μl RNAreference with 6 μl WFI as a negative control were incubated for 1 hourat 37° C.

Subsequently, the samples were analyzed using RNA gel electrophoresis.

RNA Agarose Gel Electrophoresis:

A 50 ml RNA gel (1.2%) was prepared to determine the presence of thereference RNA. 0.6 g agarose and 5 ml 10×MOPS buffer (20 mM EDTA, 200 mMMOPS, 50 mM sodium acetate pH 7.0) were added to 45 ml water andincubated at 65° C. for 15 minutes. After agarose had been completelydissolved, 0.9 mL formaldehyde solution (37%) were added, and the liquidwas poured into a horizontal gel-chamber. After the gel solidified, RNArunning buffer was added to the gel chamber (lx MOPS buffer, 0.74%formaldehyde).

The RNA samples and 10 μl of an RNA size ladder (500-6000b; single RNAsin the size of 492, 742, 992, 1490, 1992, 2991, 3964, and 6001 b, 1μg/ml) were substituted with 2 μl gel loading buffer and were run on theagarose gel (FIG. 13).

Results:

TABLE 10 Summary and analysis of the test for RNA contaminationIntegrity values Integrity of RNA incubated with DNA (IN_(P)) 84.0%Integrity of RNA negative control (IN_(C)) 89.2% Relative Difference(IN_(P) − IN_(C))/IN_(C) 5.8% Specific length Specific length of theRNA, incubated with DNA (SL_(P)) −0.03 Specific length of RNA negativecontrol (SL_(C)) −0.04 Absolute Difference (SL_(P) − SL_(C)) 0.01

The incubation of a reference RNA with the linear plasmid DNA resultedin an integrity of 84% compared to an integrity of 89.2% of the controlRNA and therefore was applicable for in vitro transcription.

Example 20: Large-Scale RNA In Vitro Transcription

A large scale in vitro RNA transcription reaction using the lineartemplate DNA was conducted.

RNA In Vitro Transcription

29.7 ml linear template DNA [0.77 g/l], 92 ml Cap/NTP-mix (20 mM ATP, 20mM CTP, 20 mM UTP, 7.25 mM GTP, 29 mM m7G(5′)ppp(5′)G-Cap-analog, 92 ml5× transcription buffer (containing 400 mM HEPES, 120 mM MgCl₂, 10 mMspermidine, 200 mM DTT, 25 U/ml inorganic pyrophosphatase), 2.3 ml RNaseinhibitor [40 U/μl], 11.5 ml T7 RNA polymerase [200 U/μl] and 232.5 mlWFI were gently mixed and divided to 36 different 50 ml reaction tubes.The reactions were incubated at 37° C.

DNA Template Removal: DNase I Treatment

To digest DNA template, 3.83 ml DNase I [1 U/μl] and 127 μl 0.1M CaCl₂were added to each reaction tube (36 reactions in total) and incubatedat 37° C.

Precipitation of RNA

After DNase digest, 15.33 ml WFI and 15.97 ml 8M LiCl₂ were added to thereaction and well mixed via vortexing for 15 seconds. The 36 reactionswere incubated over night at −20° C. and subsequently centrifuged at 4°C. The supernatant was discarded, and the RNA pellets were washed with10 ml 75% ethanol and centrifuged for 10 minutes at 4° C. Thesupernatant was discarded, and the RNA pellets were again washed with 10ml 75% ethanol and centrifuged for 1 minute. After discarding thesupernatant, the remaining ethanol was carefully removed with a pipette.Following that, the RNA pellets were dried at room temperature.

Re-Suspension of RNA

Each dried RNA pellet was re-suspended in 10 ml WFI. Following that, the36 reactions were pooled. The RNA concentration of the sample wasdetermined photometrically (Table 11).

Results:

TABLE 11 Photometric determination of the RNA concentration value 1value 2 value 3 average Sample [μg/μl RNA] [μg/μl RNA] [μg/μl RNA][μg/μl RNA] RNA 2.1 2.1 2.1 2.1

Measurements were performed in triplicates, and average was calculated.

The RNA concentration of the solution was determined to be 2.1 μg/μl.Therefore, the total yield of the large-scale RNA in vitro transcription(360 ml volume) reaction was 756 mg.

Example 21: Analysis of the In Vitro Transcribed RNA (Large-ScaleReaction) by Agarose Gel Electrophoresis

The size and the band uniqueness of the in vitro transcribed RNA weredetermined by performing RNA agarose gel electrophoresis according toExample 19).

Result:

The determined RNA length was in accordance with the expected length(see FIG. 14). Moreover, no additional band was observed.

Example 22: Preparative HPLC Purification of In Vitro Transcribed RNA

The in vitro transcribed RNA was purified by a size-selective HPLC basedtechnique as described in WO2008077592. The purified RNA wasconcentrated by alcohol precipitation and re-suspended in water forinjection. The concentration of the RNA was determined by photometry.

Preparative HPLC:

A porous, nonalkylated polystyrene/divinylbenzene(polystyrenedivinylbenzene) matrix was used (PLRP-S 4000 Å 8 μm 50×25 mmcolumn) as a stationary phase. The column had a particle size of 8 μmand a pore size of 4000 Å.

The eluent buffers, eluent A (100 mM triethylammonium acetate in WFI, pH7.0) and eluent B (100 mM Triethylammoniumacetat in 25% acetonitrile, pH7.0), were de-gassed with helium. 360 ml of a 2.1 mg/ml RNA solutionobtained from the large-scale in vitro RNA transcription and 40 ml of 1Mtriethylammonium acetate (TEAA) were mixed. The RNA was step-wisepurified and fractionated. The HPLC fractions were collected, and theproduct-containing fractions (fractions 1-5 in FIG. 15) were pooled.

Detection proceeded with an UV detector at 254 nm with a referencemeasurement at 600 nm.

Pool 1: fraction 1

Pool 2: fraction 2-3

Pool 3: fraction 4-5

All 3 product pools were used for precipitation, freeze-drying(lyophilization) and subsequent quality controls.

The RNA lyophilisate was re-suspended in WFI to obtain a final RNAconcentration of approximately 5.0 g/l. Following that, RNA solution wassterile-filtered.

Determination of the RNA Concentration:

The RNA concentration of the RNA was determined photometricallyaccording to Example 20 to be 4.80 g/l. Therefore, the total yield ofthe large scale in vitro transcription, after purification was 458.4 mg.

End-Product Controls Example 23: RNA Identity Test Using RNase ATreatment

To determine the identity of the product, 8 μl WFI and 1 μg (1 μg/μl)RNA were treated with 1 μl RNase A (10 μg/μl). Additionally, oneuntreated control was prepared (1 μl RNA (1 μg/μl and 9 μl WFI). Bothreactions were incubated for 1 h at 37° C. and subsequently analyzed viaconventional RNA gel electrophoresis according to Example 21.

The results are shown in FIG. 16.

Results:

As can be seen from FIG. 18, no RNA band is detectable in the samplewith RNAse treatment.

Example 24: RNA Identity Test Using RT-PCR

RNA identity was determined by RT-PCR (Reverse transcription PCR) usingM-MuLV Reverse Transcriptase for cDNA generation by reversetranscription and a conventional PCR using gene-specific primers (primerpair I: 204-AS-FW+205-AS-RV; 799-AS-FW and 792-AS-RV).

Reverse Transcription:

2 μl RNA (50 ng/μl) were added to 9 μl WFI and 1 μl oligo dT Primer(dT)₁₈ (5 pmol/μl) and incubated for 5 min at 65° C. in a heating blockand subsequently put on ice. 4 μl 5× reaction buffer, 1 μl RNaseinhibitor (20 U/μl), 2 μl dNTP mix (10 mM) and 1 μl M-MuLV ReverseTranscriptase (200 U/μl) were added, mixed and incubated for 60 min at42° C. The reaction was stopped by incubation at 70° C. for 5 min.Subsequently, the reaction was cooled on ice.

PCR:

2 μl of the RT reaction were added to 25 μl 2×PCR Master Mix, 5 μlForward-Primer (5 pmol/μl), 5 μl Reverse-Primer (5 pmol/μl), 11.5 μl WFIand 1.5 μl DMSO (100%).

Primer Pair I for PCR reaction 1:

(SEQ ID NO: 16) Forward-Primer 204-AS-FW: CACTGCATCCGGAACAAG (SEQ ID NO: 17) Reverse-Primer 205-AS-RV: CACGTCGTTGCTGATCAC 

Primer Pair II for PCR reaction 2:

(SEQ ID NO: 18) Forward-Primer 799-AS-FW: CCAGAAGGTGACCAAGTTCA(SEQ ID NO: 19) Reverse-Primer 792-AS-RV: GCTCTGAAAAGAGCCTTTGG

PCR Program for PCR 1:

Cycles Temperature Time [min:s] 1 95° C. 2:00 30 95° C. 0:30 55° C. 0:3072° C. 0:30 72° C. 10:00  1  4° C. ∞

PCR Program for PCR 2:

Cycles Temperature Time [min:s] 1 95° C. 2:00 35 95° C. 0:30 55° C. 0:3072° C. 0:30 72° C. 10:00  1  4° C. ∞

The results of the PCR reactions were analysed by DNA gelelectrophoresis according to Example 2. The results are shown in FIG.17.

Results:

PCR reaction 1: expected size: 357 bp determined size: 341 bp PCRreaction 2: expected size: 412 bp determined size: 378 bp

Example 25: RNA Identity and Integrity Test Via RNA-Gel Electrophoresis

Size, band uniqueness, and integrity of the pure RNA pools wasdetermined by performing RNA agarose gel electrophoresis according toExample 21. Results are shown in Table 12.

TABLE 12 Results of the RNA agarose gel electrophoresis Additional bandsvisible? Band Intergity Pure RNA No 82.7Results:

For the pure RNA, no additional band was determined. Moreover bandintegrity met the quality requirements.

Example 26: Photometric Determination of the RNA Content

The RNA concentration of the pure RNA sample was again determinedphotometrically according to Example 20.

Results:

The RNA concentration of the pure RNA sample was determined to be 5.1g/l.

Example 27: Determination of the pH

Potentiometric determination of the pH content was performed using acommercially available volt-meter according to the Europeanpharmacopedia (PhEur) 2.2.3.

Results:

The pH of the RNA solution was determined to be 6.43.

Example 28: Determination of the Osmolality

The measurement of the osmolality was performed according to Europeanpharmacopedia (PhEur) 2.2.35, using a commercially available osmometer.

Results:

The osmolality was determined to be 3.7 mOsmol/kg.

Example 29: Determination of Sterility/Bioburden Using a Plating Assay

For determination of the bioburden the presence of bacteria was testedunder aerobe and anaerobe conditions after plating the RNA to agar- andglucose plates and incubation for 5 and 7 days, using a plate countmethod (according to PhEur 2.6.12.). The -test was performed accordingto Example 15.

Example 30: Determination of the Endotoxin Content of the Pure RNA

For determination of the endotoxin levels the LAL-test(kinetic-turbidimetric method) according to Ph. Eur., 7th Edition,2.6.14. was performed.

Results:

The endotoxin-level of the pure RNA was determined to be 0.25 EU/ml.

Example 31: Determination of the Protein Content of the Pure RNA

The protein content of the pure RNA sample was determined according toExample 14.

Results:

The protein content was determined to be 2.4 μg/ml.

Example 32: Determination of Residual Plasmid DNA

Residual plasmid DNA was detected via quantitative PCR using specificprimers and probes for the ampicillin gene hosted in the productionvector. Quantitative PCR to determine the contamination with templatepDNA was performed using a LightCycler and LightCycler Master Mix (RocheDiagnostics) according to the manufacturer's instructions.

The following primers and probes were used:

(SEQ ID NO: 12) Sense-Primer bla13U: GATACCGCGAGACCCAC (SEQ ID NO: 13)Antisense-Primer bla355L: GGAACCGGAGCTGAATG (SEQ ID NO: 14)Probe BL04FL: GCCAGCCGGAAGGGCC-FL (SEQ ID NO: 15)Probe BL04LC: LC Red640-GCGCAGAAGTGGTCCTGCA-PhResults:

The copy number of pDNA in the RNA was determined to be 2.5 E+03copies/μg RNA.

Example 33: Determination of Residual Genomic Bacteria DNA

Residual bacterial genomic DNA was determined according to Example 16.

Results:

Genomic DNA of E. coli was undetectable in the RNA sample.

Example 34: Determination of Residual Solvents

The determination of residual solvents in the RNA was determined usingquantitative gas-chromatography with flame ionization detector (GC-FID).

Results:

TABLE 13 Residual solvents as detected by quantitative GC. SolventDetected by GC-FID TEAA  43 ppm Isopropanol <50 ppm Chlorophorm <60 ppmAcetonitrile <40 ppm Phenol <20 ppm

The invention claimed is:
 1. A method for producing purified RNAcomprising the following steps: a) providing a template DNA comprising anucleic acid sequence encoding an RNA sequence, wherein the followingsteps are used to control the quality of the template DNA provided instep a): I) determining the concentration of the template DNA in asample; II) determining the integrity of the template DNA; III)determining the identity of the template DNA; and IV) determining thepurity of the template DNA by determining in a sample comprising thetemplate DNA: the presence of RNA; the presence of protein; the presenceof endotoxin; the presence of bacterial DNA; and the presence ofribonuclease; b) in vitro transcribing the template DNA in order toobtain a composition comprising the RNA; and c) purifying the RNA by atleast one purification step selected from the group consisting of aprecipitation step and a chromatographic step to obtain purified RNA,wherein the following steps are used to assess the quality of the RNAobtained in step b or the purified RNA obtained in step c: i)determining the concentration of the RNA or the purified RNA in asample; ii) determining the integrity of the RNA or the purified RNA;iii) determining the identity of the RNA or the purified RNA, bydetermining the length of the RNA; by digesting the RNA with aribonuclease; by determining the length of a cDNA obtained by reversetranscription (RT)-PCR using the RNA as a template; and by determiningthe sequence of a cDNA obtained by RT or RT-PCR using the RNA as atemplate; iv) determining the purity of the RNA or the purified RNA, bydetermining in a sample comprising the RNA the presence of protein; thepresence of endotoxin; the presence of bacterial DNA; the presence ofplasmid DNA; and the presence of organic solvent; v) determining the pHof a sample comprising the RNA or the purified RNA; and vi) determiningthe osmolality of a sample comprising the RNA or the purified RNA. 2.The method according to claim 1, wherein the purified RNA obtain in stepc) comprises 1 to 5 grams of RNA.
 3. The method according to claim 1,wherein the concentration of the template DNA provided in step a) isdetermined by photometric measurement.
 4. The method according to claim1, wherein the identity of the nucleic acid sequence encoding the RNAsequence, provided in step a) is determined by using at least one stepselected from polymerase chain reaction (PCR), restriction analysis orsequence analysis.
 5. The method according to claim 1, wherein thepurity of the template DNA provided in step a) is determined bydetermining in a sample comprising the template DNA the amount of RNA;the amount of protein; the amount of endotoxin; and the amount ofbacterial DNA.
 6. The method according to claim 5, wherein the amount ofbacterial DNA is determined by using a PCR method.
 7. The methodaccording to claim 6, wherein the amount of bacterial DNA is determinedusing a universal primer pair for bacterial DNA.
 8. The method accordingto claim 6, wherein the amount of E. coli DNA is determined using aprimer pair specific for E. coli DNA.
 9. The method according to claim8, wherein the primer pair is specific for the E. coli uidA gene. 10.The method according to claim 1, wherein the concentration of the RNAobtained in step b) or the purified RNA obtained in step c) isdetermined by photometric measurement.
 11. The method according to claim1, wherein the integrity of the RNA obtained in step b) or the purifiedRNA obtained in step c) is determined by determining the percentage offull-length RNA.
 12. The method according to claim 1, wherein theidentity of the RNA obtained in step b) or the purified RNA obtained instep c) is determined by determining the length of the RNA; by digestingthe RNA with a ribonuclease; by determining the length of a cDNAobtained by reverse transcription (RT)-PCR using the RNA as a template;by oligonucleotide mapping; by determining the sequence of the RNA byRNA sequencing; and by determining the sequence of a cDNA obtained by RTor RT-PCR using the RNA as a template.
 13. The method according to claim1, wherein the purity of the RNA obtained in step b) or the purified RNAobtained in step c) is determined by determining in a sample comprisingthe RNA the amount of protein; the amount of endotoxin; the amount ofbacterial DNA; and the amount of plasmid DNA.
 14. The method accordingto claim 13, wherein the amount of bacterial DNA is determined by usinga PCR method.
 15. The method according to claim 14, wherein the amountof bacterial DNA is determined using a universal primer pair forbacterial DNA.
 16. The method according to claim 14, wherein the amountof E. coli DNA is determined using a primer pair specific for E. coliDNA.
 17. The method according to claim 16, wherein the primer pair isspecific for the E. coli uidA gene.
 18. The method according to claim 1,wherein step a) comprises selecting an RNA sequence.
 19. The methodaccording to claim 1, wherein step a) comprises synthesis of thetemplate DNA.
 20. The method according to claim 1, wherein the templateDNA is a DNA plasmid.
 21. The method according to claim 20, furthercomprising, prior to step a) culturing bacteria comprising the plasmidunder selective conditions; isolating the template DNA from the bacteriaand linearization of the template DNA; wherein the purity of thetemplate DNA provided in step a) is determined by determining in asample comprising the template DNA the amount of RNA; the amount ofprotein; the amount of endotoxin; the amount of bacterial DNA; and thepresence of ribonuclease; wherein the identity of the RNA obtained instep b) or the purified RNA obtained in step c) is determined bydetermining the length of the RNA; by digesting the RNA with aribonuclease; by determining the length of a cDNA obtained by reversetranscription (RT)-PCR using the RNA as a template; and by determiningthe sequence of a cDNA obtained by RT or RT-PCR using the RNA as atemplate; wherein the chromatographic step comprises HPLC; and whereinthe purity of the RNA obtained in step c) is determined by determiningin a sample comprising the RNA the amount of protein; the presence ofendotoxin; the amount of bacterial DNA; the amount of plasmid DNA; andthe presence of organic solvent.
 22. The method according to claim 20,wherein step a) comprises linearization of the template DNA.
 23. Themethod according to claim 1, wherein the in vitro transcription in stepb) is carried out in presence of modified nucleotides.
 24. The methodaccording to claim 1, wherein the in vitro transcription in step b) iscarried out in presence of a cap analog.
 25. The method according toclaim 1, wherein the precipitation step is an alcoholic precipitationstep or a LiCl precipitation step.
 26. The method according to claim 1,wherein the chromatographic step is selected from the group consistingof HPLC, anion exchange chromatography, affinity chromatography,hydroxyapatite chromatography and core bead chromatography.
 27. Themethod according to claim 1, wherein the RNA obtained in step b) ispurified by at least one first and at least one second purificationstep.
 28. The method according to claim 27, wherein the at least onefirst purification step comprises a precipitation step and the at leastone second purification step comprises a chromatographic step.
 29. Themethod according to claim 27, wherein the at least one firstpurification step comprises a LiCl precipitation step and the at leastone second purification step comprises a step of RP-HPLC.
 30. The methodaccording to claim 1, wherein the RNA obtained in step b) or thepurified RNA obtained in step c) is lyophilized.
 31. The methodaccording to claim 1, wherein the presence of protein in the templateDNA and the purified RNA is not determined by a Bradford assay.
 32. Themethod according to claim 1, wherein the presence of protein in thetemplate DNA or the purified RNA is determined by a Bichinonic Acid(BCA) assay.
 33. The method according to claim 31, further comprisingdetermining the amount of protein in the template DNA or the purifiedRNA by the BCA assay.
 34. The method according to claim 1, wherein theamount of protein in the purified RNA is determined by a Bichinonic Acid(BCA) assay.